| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Regular Articles |
From the Department of Pathology, Hirosaki University School of Medicine, Hirosaki, Japan
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The Goto-Kakizaki (GK) rat is a spontaneous animal model of NIDDM without obesity.8 This model was produced by repeated selective breeding of rats with glucose intolerance starting from a nondiabetic Wistar rat colony.8 The GK rats exhibit mild hyperglycemia at fast and an impaired glucose tolerance on glucose load.9-11 With progression of the disease, this diabetic model develops characteristic complication-like tissue damage in the peripheral nerves as well as kidneys, recapitulating systemic manifestations encountered in human NIDDM.8 The exploration of islet changes in this model is, therefore, extremely important to clarifying the pathogenesis of human NIDDM.
Histopathological changes in the endocrine pancreas in GK rats include
irregular shape, fibrosis, and progressive depletion of islet ß cells
commencing at 8 weeks of age in the Stockholm colony8,12
or, soon after birth, at 4 days of age in the Paris
colony.13,14
In our preceding studies, we found islet-cell
degeneration and reduction of islet ß-cell volume in GK rats of the
Japanese colony from 8 weeks of age, which had further progressed with
aging.15
We also found that the reduction of ß-cell
volume was inhibited by the correction of hyperglycemia with the
administration of 
-glucosidase inhibitor.15
These
results led us to hypothesize that glucose toxicity (continuous
hyperglycemia) may accelerate ß-cell reduction in GK rats. To explore
the mechanisms of progressive loss of islet ß cells in GK rats, we
examined whether continuous elevation of hyperglycemia under sucrose
feeding accelerates the depletion of pancreatic ß cells and whether
the ß-cell loss is related to oxidative stress, proliferative
activity, and oncogenic expression of Bcl-2 and Bax.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
GK rats were obtained from the colony bred in the Takeda Research Institute (Takeda Chemical Industries, Ltd., Osaka, Japan), which originated from the colony at Tohoku University.8 Nondiabetic Wistar rats were obtained from the same laboratory and used as controls. All animals had free access to tap water and standard rat chow (Oriental Yeast, Tokyo, Japan) until the experiment. At 6 weeks of age, both GK rats and control Wistar rats were randomly allocated to one of two groups, with and without sucrose feeding. For treatment groups, 30% sucrose in drinking water (w/v) was given for 2 and 6 weeks after 6 weeks of age.
During the experimental period, body weights and nonfasting blood glucose concentrations were regularly measured. Blood samples were obtained by tail snipping, and nonfasting blood glucose values were determined by the glucose oxidase method (Toecho Super II, Kagawa, Japan). An oral glucose tolerance test was performed at 6, 8, and 12 weeks of age. To examine the proliferative activity of the islet cells, rats were fasted overnight and injected intraperitoneally with 5-bromo-2'-deoxyuridine (BrdU) (Boehringer Mannheim GmbH, Mannheim, Germany) dissolved in phosphate-buffered saline at a dose of 100 mg/kg body weight.16 After 4 hours, the pancreata were dissected free from adjacent tissues under deep anesthesia with 50 mg/kg pentobarbital (Abbott Laboratories, Chicago, IL). The whole pancreas was cleared of extraneous fat and lymph nodes and weighed. All specimens surgically obtained were fixed in 10% formalin solution and embedded in paraffin.
Glucose Tolerance Test and Fasting Plasma Insulin Levels
After an overnight fast, all animals were orally given a glucose solution (2 g/kg body weight), and their blood glucose levels were determined from the tail blood at 0, 30, 60, and 120 minutes afterwards with the glucose oxidase method using Toecho Super II. Levels of immunoreactive insulin in the plasma during fasting were estimated using an insulin kit (Morinaga, Yokohama, Japan).
Immunohistochemistry and Morphometry of Islet ß and Cells
After reviewing the slides stained with hematoxylin and eosin,
contiguous paraffin sections 4 µm thick were prepared for
immunocytochemical staining and morphometric analysis of islet ß and
cells. To identify the areas of and ß cells in the islets,
immunoperoxidase double staining was performed using the Histostain DS
kit (Zymed Laboratories, San Francisco, CA). Briefly, deparaffinized
sections were first incubated with rabbit anti-glucagon antibody
(diluted 1:2000, raised in our laboratory) for 1 hour at room
temperature preceded by inhibition of endogenous peroxidase activity
with 0.3% hydrogen peroxide for 30 minutes. Then, the slides were
incubated at room temperature with biotinylated anti-rabbit
immunoglobulin antibody and alkaline phosphatase-conjugated
streptavidin for 30 minutes in each. The alkaline phosphatase reaction
was detected by a new fuchsin method using naphthol-AS-BI-phosphate
(Sigma Chemical Co., St. Louis, MO) as a substrate and
hexazotized new fuchsin (Sigma Chemical Co.) as a
coupler. Before the incubation of the second antigen detection,
the sections were treated with double staining enhancer (Zymed
Laboratories) for 30 minutes at room temperature. After rinsing with
phosphate-buffered saline, followed by treatment with normal goat serum
for 15 minutes, the sections were incubated with rabbit anti-insulin
antibody (1:200, raised in our laboratory) for 1 hour at 37°C. They
were incubated again with biotinylated immunoglobulin and
peroxidase-conjugated streptavidin (Histofine, Nichirei, Tokyo, Japan).
Finally, the secondary reaction products were visualized with
nickel-diaminobenzidine (0.02% 3,3'-diaminobenzidine (Wako, Osaka,
Japan), 0.05% NiCl2, and 0.03%
H2O2). Nuclei were counterstained lightly with
hematoxylin.
Quantitative evaluation of the islet cell areas was performed
using a computer-assisted point-counting method on an Olympus AX80
microscope connected to a personal computer system using NIH Image
(version 1.56). Calculation of the volume density of and ß cells
with the point-counting method was based on previously described
methods.4,17
First, even distribution of islets was
confirmed, and fields for morphometric analysis were randomly selected
in all experimental animals. A high-magnification (x200) image of
double immunostaining sections was overlaid with a grid consisting
of 875 points. In each animal, 25 to 80 fields (average, 45)
were subjected for the quantitation of endocrine cells. Total
number of the points hit on ß or cells ranged from 21,875 to
70,000 (average, 40,000). Volume densities of ß and cells
were determined by division of total points hit on insulin- or
glucagon-stained cells divided by total points hit on pancreatic
parenchyma, respectively. Areas of blood vessels, nerves, fat, and
connective tissues were excluded from the measurement. During the
process of morphometric analysis, the identity of the samples was
masked to the examiners.
Proliferative Activity of Pancreatic ß Cells
To examine proliferative activity of ß cells, BrdU-insulin double immunostaining was carried out. First, deparaffinized sections were incubated with rabbit anti-insulin antibody (1:200) for 1 hour at 37°C, followed by incubation with the second biotinylated rabbit immunoglobulin and then with alkaline phosphatase-conjugated streptavidin. After visualization with naphthol AS-BI phosphate and a thorough rinsing with phosphate-buffered saline, the sections were treated with microwave irradiation (H2500 microwave processor, Bio-Rad Laboratories, Hercules, CA) in 0.01 mol/L citrate buffer (pH 6.0) for antigen retrieval. They were then treated with pepsin in 0.1 N HCl (50 mg/ml, Sigma Chemical Co.) for 30 minutes at 37°C. The sections were finally incubated with monoclonal antibody to BrdU (diluted 1:1, Zymed Laboratories) overnight at 4°C, followed by incubation with the second biotinylated mouse immunoglobulin and third peroxidase-conjugated streptavidin and visualized with nickel-diaminobenzidine as described above. In each section, the number of positive cells among approximately 4000 insulin-positive cells (BrdU/insulin index) were counted at high magnification (x400) as an index of proliferative activity and are expressed as a percentage.
In Situ Detection of Apoptotic Cells
The deparaffinized sections were incubated with the terminal deoxynucleotide transferase-mediated nick end labeling (TUNEL) method using the ApopTag in situ apoptosis detection kit (Oncor, Inc., Gaithersburg, MD).18 After visualization of apoptotic cells with nickel-diaminobenzidine, immunostaining for insulin was performed as described above. The cells showing black nuclei and red cytoplasm were defined as apoptotic ß cells. In each sample, the number of apoptotic cells among approximately 4000 cells as an apoptotic index (TUNEL/insulin index) was counted at a high magnification (x400) and is expressed as a percentage.
Immunostaining of 8-Hydroxy-Deoxyguanosine, Bcl-2, and Bax
To evaluate the location of oxidative stress, the deparaffinized sections were incubated with monoclonal antibody to 8-hydroxy-deoxyguanosine (8-OH-dG; diluted 1:1; Jika, Shizuoka, Japan) using a catalyzed signal amplification system (DAKO, Tokyo, Japan).19 For the detection of apoptosis-related oncogenic proteins, the deparaffinized sections were treated with microwave irradiation in 0.01 mol/L citrate buffer (pH 6.0) for antigen retrieval. The sections were first incubated with antibodies to 8-OH-dG. For the detection of Bcl-2 and Bax, the sections were first incubated with antibodies to Bcl-2 (diluted 1:50, Santa Cruz Biotech, Inc., Santa Cruz, CA) or Bax (diluted 1:50; Santa Cruz) overnight at 4°C, followed by incubation with the second biotinylated rabbit immunoglobulin and third alkaline phosphatase-conjugated streptavidin as described above. The reactions were colorized with new fuchsin. The immunoreactions of Bcl-2 and Bax were similar in most of the islets in each animal, and intensity of the Bcl-2 staining reaction on the islet was graded semiquantitatively, as follows: -, negative; +, weakly positive (lightly stained but clearly differentiated from negative background); 2+, moderately positive (between weak and strong); and 3+, strongly positive (bright red with high contrast).
Statistical Analysis
Results are expressed as means ± SD. Comparisons were made using a one-way analysis of variance, followed by post-hoc Bonferroni's corrections. Statistical significance was obtained when P values were less than 0.05.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
During the observation period, mean body weights were
significantly (P < 0.01) lower in GK rats than
those in age-related nondiabetic Wistar rats (Table 1)
. There were significant reductions in
body weight in both 8-week-old (P < 0.01) and
12-week-old Wistar rats (P < 0.01) when they
were given sucrose for 2 and 6 weeks, whereas sucrose feeding for 6
weeks did not affect body weights in GK rats (Table 1)
.
|
. Glucose Tolerance Test
On oral glucose tolerance tests, blood glucose levels after
glucose load were markedly elevated in GK rats compared with Wistar
rats. With sucrose feeding for 6 weeks, there was further elevation of
glucose levels, representing 123% and 127% of 60-minute and
120-minute values of untreated GK rats, respectively (Figure 1)
.
|
Mean basal plasma insulin levels in GK rats were nearly twice the
values of age-matched Wistar controls. These values were increased
twofold in both GK and Wistar rats with sucrose treatment (Table 2)
.
|
The pancreas of GK rats was free from the changes of pancreatitis
or insulitis. Islets of GK rats were oval or round with smooth
circumference at 6 and 8 weeks of age, whereas they became fibrotic
with irregular contour at 12 weeks of age (Figure 2)
. Sucrose-fed GK rats showed vacuolated
degeneration of islet cells, and many islets underwent marked fibrosis
with vacuolar degeneration of endocrine cells in 12-week-old GK rats
treated with sucrose for 6 weeks (Figure 2)
.
|
. On the other hand, there was no
significant difference in the mean volume density of cells between
GK rats and Wistar rats during the observation period (Table 3)
.
|
The mean labeling index (LI) of islet cells as measured by BrdU
uptake became smaller in normal Wistar rats as they grew (Table 4)
. The mean LI in 8- and 12-week-old
Wistar rats was only 28% and 5.7% of that in 6-week-old ones,
respectively. GK rats showed significantly smaller LI at both 6 and 8
weeks of age by 67% and 61% compared with those in age-matched Wistar
rats, respectively (P < 0.05 and
P < 0.01). With aging, the LI in 8- and 12-week-old GK
rats was reduced further, to 25% and 6.7% of the mean value of that
in 6-week-old GK rats. Sucrose feeding elicited a slight but
insignificant increase in the LI in both normal Wistar rats and GK
rats.
|
There were no TUNEL-positive (apoptotic) cells in the islets of
both GK and Wistar rats at all of the ages examined (Table 5)
. Sucrose feeding did not induce
apoptosis in control Wistar rats. By contrast, GK rats treated with
sucrose for 2 and 6 weeks showed the presence of apoptosis in 0.023 to
0.038% and 0.034 to 0.091% of ß cells, respectively (Figure 3)
.
|
|
There were weakly positive staining reactions of 8-OH-dG in ductal
epithelial cells, smooth muscle cells of the ductal walls, and islet
cells in normal Wistar rats at all ages examined. Although the
reactions were not uniform among islets, they appeared to be stronger
in ductal cells and islet cells in GK rats compared with age-matched
Wistar rats, in particular, of 8 and 12 weeks of age (Figure 4)
. The fibrotic islets showed the most
conspicuous reactions. The staining reactions were further intensified
in some islets of sucrose-fed GK rats, whereas no apparent
alterations were found in sucrose-fed Wistar rats (Figure 4)
.
|
. Six-week-old GK rats
showed intensified staining reactions of islets with Bcl-2, and these
reactions lessened with increasing age. Semiquantitative estimation of
Bcl-2 immunostaining on the islet sections revealed about a 2.5-fold
increase in staining intensities on average in 6-week-old GK rats
compared with age-matched control Wistar rats (Table 6)
. Eight- and 12-week-old GK rats
exhibited smaller intensities than that detected in 6-week-old GK rats.
At 8 and 12 weeks of age, Bcl-2 reactions were not different between GK
and Wistar rats. Sucrose feeding did not significantly influence these
reactions. On the other hand, islets were also positively stained with
Bax in both GK and Wistar rats, and the staining intensities did not
alter with aging. There was no difference in the Bax reactions between
GK and Wistar rats. No significant changes of staining reactions with
Bax after sucrose feeding were detected in either GK or Wistar rats.
|
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
We confirmed the progressive depletion of islet ß cells in the GK
rat. With increasing age, the reduction of ß cells was more
pronounced and was associated with diabetic syndrome, characterized
by hyperglycemia and impaired glucose tolerance on glucose load.
The commencement of apparent pancreatic pathology on hematoxylin and
eosin sections at 8 weeks of age was in agreement with our previous
findings, as well as with the data from the Stockholm
colony.12,15
Further, the reduction of ß cells was found
to be accelerated in rats with sucrose feeding. With 30% sucrose, 22%
and 50% augmentation of ß-cell loss occurred, suggesting that
continuous hyperglycemia by sucrose feeding had caused more severe cell
injury to ß cells. Combined with our previous results that correction
of hyperglycemia with glucosidase inhibitor treatment prevented the
loss of ß cells,15
the current findings provide evidence
that sucrose-induced metabolic abnormalities resulted in the augmented
ß-cell loss in this model.
Our structural studies clearly demonstrated the presence of apoptosis specific to ß cells in sucrose-fed GK rats. This is the first demonstration of the in vivo occurrence of apoptosis in ß cells in diabetic rats, in particular under augmented hyperglycemia. Given that the ß-cell mass is determined by proliferation and death of ß cells, the enhanced reduction of the ß-cell mass by sucrose overload may not be dependent on proliferative activity, but may be related to an increased rate of apoptosis of ß cells. This is accounted for by the fact obtained from the present study that there was no significant difference in proliferative activity of islet ß cells between untreated and sucrose-fed GK rats and that apoptotic cells were significantly more frequent in sucrose-fed GK rats. The cellular injury to ß cells by sucrose-induced hyperglycemia is in keeping with the previous findings that ß cells exposed to high glucose concentrations both in vivo and in vitro show impaired insulin secretion or insulin synthesis, although direct correlation between structural and functional damage of ß cells has been difficult to prove.20-23 The current findings, however, underscore hyperglycemia-induced apoptosis as a major mechanism for the progressive loss of ß cells in vivo.
Strong positive reactions of islets with 8-OH-dG in sucrose-fed GK rats suggest that oxidative stress may be a major process for ß-cell apoptosis in GK rats. In in vitro experiments, ambient high glucose gives rise to greater oxidative stress and DNA cleavage of ß cells, resulting in apoptosis. One of the relevant factors is suggested to be increased glycation.24 Treatment with aminoguanidine, an inhibitor of glycation production,25 was demonstrated to inhibit the premature death of ß cells. By contrast, the mechanisms of progressive depletion of ß cells in untreated GK rats need to be carefully interpreted, because apoptotic cells were not detected during the whole experimental period in these rats. Lower activity of proliferation may be responsible for the loss of ß cells in untreated GK rats, which cannot compensate for the age-related increase in the volume of ß cells. Proliferative activity of islet ß cells as detected by BrdU LI was significantly less in GK rats at 6 weeks and 8 weeks of age; thereafter, there was no difference in LI between GK and Wistar rats. Sucrose feeding did not significantly alter the levels of LI. Thus, the smaller levels of BrdU LI as an innate ß-cell deficit in this model may add to the rate of progressive depletion of ß-cell loss by apoptosis, yielding a greater total loss of ß cells in sucrose-treated GK rats. One may also consider that modest hyperglycemia primarily caused by insulin resistance in this model26,27 in turn gives rise to oxidative stress to ß cells, followed by a lower rate of apoptotic cells in untreated GK rats. Rapid turnover of apoptotic cells may not allow the detection of TUNEL-positive cells at light microscopic levels in this situation. This assumption may be in part supported by the finding that 8-OH-dG staining appeared stronger in untreated GK rats compared with normal Wistar rats. Alternatively, the scavenger system for excessive oxidative stress may be poorly developed or weakened secondarily in islets of GK rats relative to normal Wistar rats and likely to undergo degeneration and loss of ß cells even with modest hyperglycemia.28
Apoptosis is regulated by a complex network, which can include myc, bcl-2, bax, p53, etc.29,30 In particular, reduced proliferative activity was found to be associated with increased expression of Bcl-2 and subsequent reduction of this gene product in untreated GK rats. Sucrose feeding did not affect the reaction of Bcl-2, which has a unique oncogenic role in cell survival by inhibiting apoptosis.31,32 Elevated expression of Bcl-2 in GK rats may be an early reactive upregulation of this protein against the ongoing apoptotic processes in this model. By contrast, there were no significant alterations of Bax expression, extensive amino acid homology with Bcl-2,33 and repressor for Bcl-231. It is likely that Bax has a minor role in the process of sucrose-induced acceleration of ß-cell apoptosis.
The natural history of pancreatic islet lesions and ß-cell pathology in human NIDDM is still unclear. Heterogeneous pathophysiological states such as impaired insulin secretion or insulin resistance may correlate with the pathological lesions. Unlike other NIDDM animal models such as Otsuka-Long-Evans-Tokushima-fatty (OLETF) and Zucker diabetic fatty (ZDF) rats, as well as Wistar fatty rats, GK rats develop a common type of NIDDM without obesity.8 The genetic loci of GK rats have been reported to be polygenic for fasting hyperglycemia, glucose intolerance, and decreased basal insulin release.34,35 Further investigations are warranted for clarification of the basic mechanisms by which ß cells undergo apoptosis, so that effective prevention may be developed for the primary prevention of NIDDM.
|
Acknowledgements |
|---|
|
Footnotes |
|---|
Accepted for publication May 8, 1998.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  B. Qian, H. Wang, X. Men, W. Zhang, H. Cai, S. Xu, Y. Xu, L. Ye, C. B Wollheim, and J. Lou TRIB3 is implicated in glucotoxicity- and oestrogen receptor-stress-induced {beta}-cell apoptosis J. Endocrinol., December 1, 2008; 199(3): 407 - 416. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Numazawa, H. Sakaguchi, R. Aoki, T. Taira, and T. Yoshida Regulation of the susceptibility to oxidative stress by cysteine availability in pancreatic {beta}-cells Am J Physiol Cell Physiol, August 1, 2008; 295(2): C468 - C474. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Nugent, D. M. Smith, and H. B. Jones A Review of Islet of Langerhans Degeneration in Rodent Models of Type 2 Diabetes Toxicol Pathol, June 1, 2008; 36(4): 529 - 551. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M.-K. Sim, X.-G. Xu, Y.-C. Wong, S.-Z. Sim, and K.-O. Lee Des-Aspartate-Angiotensin I Exerts Hypoglycemic Action via Glucose Transporter-4 Translocation in Type 2 Diabetic KKAy Mice and GK Rats Endocrinology, December 1, 2007; 148(12): 5925 - 5932. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q. Huang, S. Bu, Y. Yu, Z. Guo, G. Ghatnekar, M. Bu, L. Yang, B. Lu, Z. Feng, S. Liu, et al. Diazoxide Prevents Diabetes through Inhibiting Pancreatic {beta}-Cells from Apoptosis via Bcl-2/Bax Rate and p38-{beta} Mitogen-Activated Protein Kinase Endocrinology, January 1, 2007; 148(1): 81 - 91. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Dungan and J. B. Buse Glucagon-Like Peptide 1-Based Therapies for Type 2 Diabetes: A Focus on Exenatide Clin. Diabetes, April 1, 2005; 23(2): 56 - 62. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Kohler, S. V. Zaitsev, I. I. Zaitseva, B. Leibiger, I. B. Leibiger, M. Turunen, I. L. Kapelioukh, L. Bakkman, I. B. Appelskog, J. Boutet de Monvel, et al. On-Line Monitoring of Apoptosis in Insulin-Secreting Cells Diabetes, December 1, 2003; 52(12): 2943 - 2950. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S.-J. Janket, J. E. Manson, H. Sesso, J. E. Buring, and S. Liu A Prospective Study of Sugar Intake and Risk of Type 2 Diabetes in Women Diabetes Care, April 1, 2003; 26(4): 1008 - 1015. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Tourrel, D. Bailbe, M. Lacorne, M.-J. Meile, M. Kergoat, and B. Portha Persistent Improvement of Type 2 Diabetes in the Goto-Kakizaki Rat Model by Expansion of the {beta}-Cell Mass During the Prediabetic Period With Glucagon-Like Peptide-1 or Exendin-4 Diabetes, May 1, 2002; 51(5): 1443 - 1452. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Wobser, H. Du{beta}mann, D. Kogel, H. Wang, C. Reimertz, C. B. Wollheim, M. M. Byrne, and J. H. M. Prehn Dominant-negative Suppression of HNF-1alpha Results in Mitochondrial Dysfunction, INS-1 Cell Apoptosis, and Increased Sensitivity to Ceramide-, but Not to High Glucose-induced Cell Death J. Biol. Chem., February 15, 2002; 277(8): 6413 - 6421. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Tourrel, D. Bailbe, M.-J. Meile, M. Kergoat, and B. Portha Glucagon-Like Peptide-1 and Exendin-4 Stimulate {beta}-Cell Neogenesis in Streptozotocin-Treated Newborn Rats Resulting in Persistently Improved Glucose Homeostasis at Adult Age Diabetes, July 1, 2001; 50(7): 1562 - 1570. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Federici, M. Hribal, L. Perego, M. Ranalli, Z. Caradonna, C. Perego, L. Usellini, R. Nano, P. Bonini, F. Bertuzzi, et al. High Glucose Causes Apoptosis in Cultured Human Pancreatic Islets of Langerhans: A Potential Role for Regulation of Specific Bcl Family Genes Toward an Apoptotic Cell Death Program Diabetes, June 1, 2001; 50(6): 1290 - 1301. [Abstract] [Full Text]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
, Wistar rats; 
, sucrose-fed Wistar rats; 
, GK rats; 
sucrose-fed GK rats.
