Implementation of a Molecular Tumor Board: The Impact on Treatment Decisions for 35 Patients Evaluated at Dartmouth-Hitchcock Medical Center

BACKGROUND

Although genetic profiling of tumors is a potentially powerful tool to predict drug sensitivity and resistance, its routine use has been limited because clinicians are often unfamiliar with interpretation and incorporation of the information into practice. We established a Molecular Tumor Board (MTB) to interpret individual patients' tumor genetic profiles and provide treatment recommendations.

PATIENTS AND METHODS

DNA from tumor specimens was sequenced in a Clinical Laboratory Improvement Amendments-certified laboratory to identify coding mutations in a 50-gene panel (n = 34) or a 255-gene panel (n = 1). Cases were evaluated by a multidisciplinary MTB that included pathologists, oncologists, hematologists, basic scientists, and genetic counselors.

RESULTS

During the first year, 35 cases were evaluated by the MTB, with 32 presented for recommendations on targeted therapies, and 3 referred for potential germline mutations. In 56.3% of cases, MTB recommended treatment with a targeted agent based on evaluation of tumor genetic profile and treatment history. Four patients (12.5%) were subsequently treated with a MTB-recommended targeted therapy; 3 of the 4 patients remain on therapy, 2 of whom experienced clinical benefit lasting >10 months.

CONCLUSION

For the majority of cases evaluated, the MTB was able to provide treatment recommendations based on targetable genetic alterations. The most common reasons that MTB-recommended therapy was not administered stemmed from patient preferences and genetic profiling at either very early or very late stages of disease; lack of drug access was rarely encountered. Increasing awareness of molecular profiling and targeted therapies by both clinicians and patients will improve acceptance and adherence to treatments that could significantly improve outcomes.

IMPLICATIONS FOR PRACTICE

Case evaluation by a multidisciplinary Molecular Tumor Board (MTB) is critical to benefit from individualized genetic data and maximize clinical impact. MTB recommendations shaped treatment options for the majority of cases evaluated. In the few patients treated with MTB-recommended therapy, disease outcomes were positive and support genetically informed treatment.

Abstract P3-12-09: Factors influencing aromatase inhibitor induced musculoskeletal syndrome: Roles of menopause timing and osteoporosis therapy

Background: Aromatase Inhibitor (AI) therapy is the most effective hormonal treatment in post-menopausal estrogen receptor (ER) positive breast cancer. Side effects such as arthralgias - termed aromatase inhibitor induced musculoskeletal syndrome (AIMSS) - limit their use in some patients. We evaluated factors associated with AIMSS and explored possible therapeutic options in a large cohort of patients.

Methods: We performed an IRB-approved retrospective review of breast cancer patients seen in the Norris Cotton Cancer Center clinics from April 2011 to January 2013. 378 patients were included in our chart review on the basis of taking an AI for breast cancer with follow up documented in the electronic health record. Statistical analysis was performed by chi squared test for dichotomous variables and students t-test for continuous variables.

Results: In our cohort 91% of patients were taking an AI as adjuvant therapy (9% for metastatic disease) with 41% (n=153) reporting new or worsening arthralgias after initiation of an AI. AIMSS was 42.5%(95%CI: 0.375 to 0.478) in the adjuvant and 22.7%(95%CI: 0.101 to 0.434) in the metastatic groups. The median time to symptom onset was 120 days. 2.1% (n=8) discontinued AI therapy due to AIMSS. There was no association with prior chemotherapy, baseline arthralgia, BMI, or statin use. We found an increased risk of developing AIMSS with more recent menopause (p=0.055), and therapy in the adjuvant setting (p=0.067). We also note a potential association of baseline osteoporosis and osteoporosis therapies with lower rates of AIMSS. Treatments included temporary discontinuation of AI, switching between AI, and non-steroidal anti-inflammatory therapy (NSAIDs). Of those attempting such treatment, all had improvement with temporary discontinuation, 25% improved after AI switch, and 85% had symptomatic benefit on NSAIDs.

Conclusions: The incidence of AIMSS in our review was 41%. Patients treated in the metastatic setting may have a lower rate of AIMSS. Our cohort revealed that more recent menopause did seem to be a risk factor. Baseline osteoporosis and osteoporosis treatments have a potential association to be explored. Management options included switching between AIs, temporary discontinuation, and NSAID treatment. Updated analysis will be presented.

Potential risk factors for the development of AIMSSCharacteristicN(-)Arthralgia N(%)(+)Arthralgia N(%)p-valueType of AI UsedAnastrozole204112(55.9)92(45.1)0.19Letrozole13183(63.4)48(36.6)Exemestane3623(64.9)13(36.1)Menopause timingLMP < 5 years prior to AI start15179(52.3)72(47.7)0.055LMP 5-10 years prior to AI start4023(57.5)17(42.5)LMP > 10 years prior to AI start155102(65.8)53(34.2)Type of therapyAdjuvant348200(57.5)148(42.5)0.067Metastatic2217(77.3)5(22.7)Baseline T-score by DEXA ScanNormal (T-score 0 to -1.49)11255(49.1)57(50.9)0.049Osteopenia (T-score -1.5 to -2.49)17196(56.1)75(43.9)Osteoporosis(T-score < -2.5)4029(72.5)11(27.5)On active osteoporosis therapy†(-) Therapy218118(54.1)100(45.9)0.03(+) Therapy12781(63.8)41(32.3)† Bisphosphonate/denosumab; LMP=Last menstrual period, AI=Aromatase Inhibitor, DEXA=Dual-energy x-ray absorptiomotry

Citation Format: Clinton R Morgan, Zsolt Kulcsar, Jonathan D Jones, William F Rigby, Peter A Kaufman. Factors influencing aromatase inhibitor induced musculoskeletal syndrome: Roles of menopause timing and osteoporosis therapy [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-12-09.

Prevention and delay in progression of human squamous cell carcinoma of the head and neck in nude mice by stable overexpression of the opioid growth factor receptor

This study examined overexpression of the opioid growth factor receptor (OGFr) in squamous cell carcinoma of the head and neck and phenotypic repercussions on tumorigenicity. Tumors from 3 SCC-1 cell lines (OGFr-9, OGFr-18, OGFr-22) stably transfected with OGFr cDNA (OGFr-1) had 2.5- to 3.7-fold more OGFr than empty vector (EV) or wild-type (WT) neoplasias. No differences in OGFr number were detected between tumors of EV and WT animals. Only 16 and 28% of the mice in the OGFr-18 and OGFr-22 groups, respectively, receiving 2 million tumor cells had a measurable tumor on day 12 compared to 70% of the EV group; 25% of the OGFr-22 animals given 5 million cells expressed a tumor relative to the EV group (100%). Latencies for tumor appearance were extended by 25 and 80% for animals in the OGFr-18 and OGFr-22 groups, respectively, compared to EV animals given 2 million cells, and were lengthened by 2-fold in OGFr-22 animals injected with 5 million cells. Tumor weight of all animals overexpressing OGFr were 48-67% of EV mice, and the number of cells undergoing DNA synthesis in these tumors with amplified OGFr was reduced 46-65% of the EV group. Tumor volumes of OGFr-9 animals inoculated with 2 million cells and followed for over 7 weeks were reduced 36-70% from the WT group on days 31-54. Tumor weights on day 54 for the OGFr-9 group were 2.6-fold less than those for the WT animals. These data support OGFr gene function as a regulator of cell proliferation that impacts on tumorigenic expression of SCCHN, and suggests that molecular and pharmacological manipulation of OGFr may prevent or delay human head and neck squamous cell cancers.

Prevention and delay in progression of human pancreatic cancer by stable overexpression of the opioid growth factor receptor

This study examined overexpression of the opioid growth factor receptor (OGFr) in pancreatic cancer cells and phenotypic changes in tumorigenicity. Tumors of MIA PaCa-2 cells transfected with OGFr cDNA (OGFr-1) had 3.3 times more OGFr than empty vector (EV) neoplasias, and 4.3 times more OGFr than tumors from wild-type (WT) mice. No differences in OGFr binding were detected between tumors of EV and WT animals. Tumor incidence in OGFr-1 animals was reduced by up to 50% from EV mice. Latency times for OGFr-1 tumor expression were increased 30%, tumor volume was decreased 70%, and DNA synthesis was reduced 24% relative to EV mice. Exogenous OGF reduced OGFr-1 tumor volume up to 55% compared to OGFr-1 mice given vehicle. These data support OGFr gene function as a regulator of cell proliferation that impacts on tumorigenic expression, and suggest that molecular and pharmacological manipulation of OGFr may prevent or delay human pancreatic cancer.

Digoxin and digoxin derivative induced arrhythmias: in vitro binding and in vivo abolition of arrhythmias by digoxin immune Fab (DIGIBAND)

OBJECTIVE

The aim was to compare the binding characteristics of a highly purified digoxin specific antigen binding fragment (digoxin immune Fab: DIGIBIND) with digoxin and with two commonly used derivatives of digoxin, beta methyl digoxin and beta acetyl digoxin, and to assess its ability to abolish the arrhythmogenic effects of these digitalis glycosides.

METHODS

The binding characteristics of DIGIBIND with digoxin, beta methyl digoxin, and beta acetyl digoxin were assessed in vitro by measuring their ability to inhibit the binding of DIGIBIND to 3H-digoxin. From these studies the affinities of the interactions between DIGIBIND and these glycosides, and the binding capacity of DIGIBIND for each of these glycosides, could be measured. The ability of DIGIBIND to abolish the arrhythmogenic effects of digoxin, beta methyl digoxin, and beta acetyl digoxin was assessed using an in vivo anaesthetised guinea pig model (n = 36, weight 300-400 g), in which these glycosides were infused intravenously (50 micrograms.kg-1 x min-1) until the onset of ventricular arrhythmias, at which point the total amount of glycoside given was calculated. A single bolus dose of either vehicle or DIGIBIND was then given intravenously, and the time to restoration of normal cardiac rhythm noted. After the administration of DIGIBIND, a second infusion of the same glycoside was given to reinitiate the ventricular arrhythmias. The time to onset of the arrhythmias was noted, and the additional amount of glycoside given calculated.

RESULTS

In vitro studies showed the binding of DIGIBIND to 3H-digoxin to be inhibited by digoxin and by the two derivatives. The affinities of these interactions with DIGIBIND were significantly different, that for digoxin being some twofold greater than that for beta methyl digoxin and beta acetyl digoxin. The ED50 concentrations were 14.1 (95% CI 12.2, 15.2), 29.2(26.1, 32.7), and 36.2(33.0, 39.8) nM, respectively. However, there were no significant differences between these glycosides in their binding capacities. The in vivo studies showed that intravenous infusion of digoxin, beta methyl digoxin, or beta acetyl digoxin induced similar ventricular arrhythmias. The onset of the arrhythmias was clearly discernible, and required a significantly lower dose of digoxin compared with that of beta methyl digoxin and beta acetyl digoxin. These doses were 667(SEM 55), 868(33), and 854(40) nmol.kg-1, respectively. Termination of the infusion had no effect on the arrhythmias, and in those animals which received a bolus intravenous injection of saline there was no return to normal cardiac rhythm. By contrast, in animals which received a bolus intravenous injection of DIGIBIND, there was complete abolition of the arrhythmias within 4-6 min. Although the dose of DIGIBIND given to abolish digoxin induced arrhythmias was approximately 25% less than that given to abolish beta methyl digoxin and beta acetyl digoxin induced arrhythmias (p < 0.05), the time to restoration of normal cardiac rhythm after DIGIBIND was not significantly different for digoxin compared with beta methyl digoxin and beta acetyl digoxin, at 4.6(0.9), 4.9(0.8), and 5.7(0.8) min, respectively. To reinitiate the arrhythmias in those animals which had received DIGIBIND, a dose of glycoside was required which was not significantly different from that given prior to the DIGIBIND. This observation therefore confirmed the stoichiometric relationship between DIGIBIND and each of the glycosides in respect of the neutralising action of DIGIBIND in abolishing the arrhythmogenic effects of these agents.

CONCLUSIONS

Although there is some small difference in the affinities of the binding interactions, there is no difference in the binding capacities of DIGIBIND for digoxin, beta methyl digoxin, or beta acetyl digoxin in vitro. These binding interactions are manifest as the ability of DIGIBIND to abolish the arrhythmogenic effects of digoxin and the two derivatives in vivo.

Influence of developmental auditory deprivation on neuronal ultrastructure in the mouse anteroventral cochlear nucleus

Developmental auditory deprivation caused mouse anteroventral cochlear nucleus neurons to have significantly fewer auditory nerve terminals and more non-auditory nerve terminals. This suggested that stimulation regulated the developmental arborization of auditory nerve terminals and competition for synaptic space. Intracellularly, mitochondria were smaller and darker in the deprived neurons and appeared less active metabolically. Interference with these neuronal processes may underlie the impaired development seen in auditory deprivation.

Stimulation-dependent development of neuronal cytoplasm in mouse cochlear nucleus

The extent of neuronal development in the mouse ventral cochlear nucleus was examined in normal and developmentally auditory deprived mice. Mice were unilaterally deprived on postnatal day three by external auditory meatus removal and sacrificed with controls on day 45, which is after the developmental period. Light microscopic morphometry of neuronal nucleus and cytoplasm areas demonstrated that the normal spherical and globular cells were larger in their low frequency regions than in their high frequency regions. This size difference occurred mainly in the cytoplasm. Developmental deprivation reduced neuronal cytoplasm areas similarly in the high and low frequency regions of both neuronal types, but had no effect on the size of the neuronal nucleus. It was interpreted that cytoplasmic metabolic events are dependent on developmental levels of stimulation and high and low frequency regions normally are differentially stimulated. Furthermore, these stimulation-dependent cytoplasmic events are impaired by developmental hypostimulation, which retards neuronal metabolism and growth. No changes were observed in the cochlear nucleus contralateral to the deprived side, suggesting that compensatory changes, such as hypertrophy, did not occur.

In vitro pharmacodynamics of 1-beta-D-arabinofuranosylcytosine: synergy of antitumor activity with cis-diamminedichloroplatinum(II)

1-beta-D-Arabinofuranosylcytosine (ara-C) was tested at a concentration of 10 micrograms/ml in the human tumor colony-forming assay against 55 human tumors of various histological types. Using the criterion for sensitivity of at least 70% inhibition of colony formation, 12 tumors (22%) were sensitive to ara-C. ara-C was most active against lung tumors (3 of 8 tumors were sensitive), and melanomas (6 of 8 sensitive). However, ara-C was not active against breast cancer (0 of 7) or colon cancer (0 of 3), and only 1 of 13 ovarian cancers was sensitive to ara-C. The activity of ara-C against melanoma and other solid tumors was confirmed using a thymidine incorporation assay. The time (t) and concentration (C) dependency of the cytotoxicity of ara-C and other chemotherapeutic agents was determined. Most agents such as Adriamycin, cis-diamminedichloroplatinum(II) (cis-platinum), and bleomycin were found to follow the C x t rule. That is, as the drug concentration was doubled, an equivalent amount of cell kill was achieved in half the time. However, the activity of ara-C was more concentration dependent than time dependent. ara-C was more effective when cells were exposed to high concentrations for short time periods. Synergy of activity between ara-C and cis-platinum was demonstrated in the breast 231 and melanoma M19 cell lines. No synergy of interaction between these two drugs was observed in the colon HT29 and lung P3 cell lines. When fresh biopsy specimens were tested with the combination, there was evidence of a synergistic interaction in 9 of 36 (25%). Maximum cytotoxicity was obtained when cells were exposed to ara-C 2 h before the addition of cis-platinum. The addition of cis-platinum before ara-C decreased the synergism.

Clinical application of the thymidine incorporation assay

An improved method for testing human tumors against chemotherapeutic agents was developed. Drug effects were quantitated in the thymidine incorporation assay (TIA) by measuring inhibition of deoxyribonucleic acid (DNA) synthesis by the proliferating cell population following exposure to anticancer drugs. Results were obtained within five days. A total of 480 out of 568 tumors received were evaluable for an overall growth rate of 85 percent. Even small biopsy specimens could be successfully grown. In 126 correlations with clinical response, the TIA had a prediction accuracy for sensitivity of 51 percent and a prediction accuracy for resistance of 97 percent. Because it is rapid, has a high growth rate, and is not subject to clumping and other cellular artifacts, the TIA represents a significant improvement over colony counting assays for predicting drug effects in human tumors.

Age- and diabetes-related changes in tissue glucose uptake and estradiol accumulation in the C57BL/KsJ mouse

The effect of the diabetes (db/db) mutation on the age-related changes in glucose uptake and estradiol incorporation in peripheral tissues were investigated in C57BL/KsJ mice between 2 and 16 wk of age. Glucose uptake in the uterus, ovaries, pancreas, lung, liver, heart, kidney, and spleen were markedly increased in diabetic mice after the development of the hyperglycemic condition, as compared with control mice. The age-related increase in glucose uptake observed in control mice was enhanced in hyperglycemic (i.e., greater than or equal to 4 wk of age) animals. In contrast, the diabetes mutation caused a decreased estradiol uptake by the uteri, ovaries, and mesometrial fat pads at 16 wk, while having little effect in nontarget tissues of diabetic mutants. These data indicate that the diabetes mutation enhances glucose uptake, especially in estradiol target tissues (i.e., uterus, ovary), at the same time that estradiol incorporation is depressed. These results suggest that an alteration in glucose utilization by steroid-sensitive reproductive tract tissue may underlie the impaired reproductive ability in these animals. Other peripheral tissues did not demonstrate any remarkable changes in estradiol uptake, but the enhanced carbohydrate metabolism observed may relate to the subsequent age- and diabetes-related changes in tissue structure and function in these animals.

Effects of growth hormone on the in vitro maturation of fetal islets

To study the effects of growth hormone (GH) on the in vitro maturation of fetal islets, the fetal islets were cultured for 7 days in RPMI 1640 containing 10% fetal bovine serum and 11.1 mM glucose with or without GH. Culture with 1 microgram/ml of bovine GH increased the DNA content of the islets and [3H]thymidine incorporation into DNA confirming results of other investigators. In addition, however, the insulin secretory dynamics and ultrastructural morphometrics were investigated. It was found that GH-treated islets demonstrated increased insulin release during acute glucose stimulation when expressed as microunits per islet per minute. However, when insulin release during acute glucose stimulation was expressed as microunits per microgram of DNA per minute to compensate for the increased DNA content of GH-treated islets, no change in insulin release was observed compared to control islets. When GH-treated islets were perifused with a linear glucose gradient, the insulin secretory response was suppressed as indicated by changes in the threshold level, plateau level, and half-maximal response. Ultrastructural morphometric data showed that the average beta-cell volume in control and GH-treated islets was the same, eliminating the possibility that beta-cell hypertrophy occurred. Similarly, the nuclear volumes of the beta cells in control and GH-treated islets remained unchanged. This finding coupled with the observed increased DNA content and [3H]thymidine incorporation suggests that GH functions by increasing cell multiplication within the islets and not by inducing polyploidy. Finally, the volumes of cytoplasmic organelles in control and GH-treated islets were the same indicating that cytodifferentiation did not occur.

Glucose utilization by the mouse brain: influence of age and diabetes

The effects of diabetes on the age-related changes in glucose utilization by various brain regions were examined in genetically diabetic (db/db) and normal (+/?) C57BL/KsJ mice following a 10 muCi injection of [3H]2-deoxyglucose (2-DOG). Brains were collected from 2 to 16-week-old mice at 30 min postinjection with 2-DOG, and the brain regions isolated by microdissection. Glucose utilization was expressed as mumol/mg/30 min for each brain region from match-paired control +/? and db/db mice. No differences in utilization were seen in brain regions from control and db/db mice at 2 weeks of age. In contrast, the diabetic condition effectively depressed the age-related increase in glucose metabolism associated with maturation in control mice between 4 and 16 weeks of age. Of particular interest was the observation that the pituitary gland of the db/db mice did not demonstrate a maturation-associated increase in glucose utilization typical of +/? mice. By 16 weeks of age, all of the brain regions of db/db mice exhibited a depressed glucose utilization rate as compared with +/? mice. These studies demonstrate that the diabetic condition impairs the normal age-related increase in CNS glucose utilization in the mouse, and suggests that decreased glucose utilization may be causally related to diabetes-associated, CNS and peripheral neuropathy.

Effects of alloxan-induced diabetes on corpus luteum function in the pseudopregnant rat

The effects of alloxan-induced diabetes mellitus on rat ovarian structure and function were examined throughout pseudopregnancy (PSP). Animals received either saline (C) or alloxan (40 mg/kg) treatment on the day of proestrus (PA) preceding PSP or on day 1 (D-1A) of PSP (day 0 = ovulation). Serum samples were analyzed by radioimmunoassay for progesterone (P) and 17-beta-estradiol (E) levels and compared with the corresponding changes in ovarian and uterine weights in C, PA, and D-1A rats. In addition, the effects of daily treatment with 6 IU ovine insulin (AI) on serum P levels were assessed in D-1A-treated rats and compared with controls. Alloxan treatment effectively elevated blood glucose levels (P less than or equal to 0.01) in PA and D-1A groups as compared with controls or AI rats. Alloxan treatment reduced both ovarian and uterine weights of PA and D-1A groups as compared with C and AI rats. Serum P levels were significantly reduced in PA (P less than or equal to 0.01) and D-1A (P less than or equal to 0.05-0.01) rats as compared with control rats throughout PSP. Daily insulin treatment reversed the suppressive effects of D-1A treatment on serum P levels, but did not restore luteal function to control levels. Neither C nor D-1A groups exhibited any marked differences in serum E levels throughout PSP. The results of these studies indicate that the administration of alloxan before the onset of PSP effectively inhibits luteal function, whereas D-1A treatment induces early luteolysis as compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose affects in vitro maturation of fetal rat islets

Fetal pancreatic islets (21.5 days old) were cultured in RPMI 1640 containing either 2.8 or 11.1 mM glucose for 7 days. After the 7-day culture period, islets cultured in 2.8 mM glucose demonstrated a minimal first phase of insulin secretion in response to acute glucose stimulation, whereas islets cultured in 11.1 mM glucose demonstrated a biphasic insulin secretory pattern. Islets cultured in 11.1 mM glucose initiated insulin secretion at 4.4 +/- 0.1 mM glucose and plateaued at 11.6 mM glucose when exposed to a linear gradient. In addition, culture in 11.1 mM glucose increased DNA content (P less than 0.01) and [3H]thymidine incorporation (P less than 0.05) in fetal islets. However, ultrastructural morphometric analysis indicated that the actual number of beta-cells within islets cultured in either 2.8 or 11.1 mM glucose did not increase. The insulin contents of islets cultured in 2.8 and 11.1 mM glucose were 0.46 +/- 0.06 and 1.14 +/- 0.10 mU/islet, respectively. During subsequent glucose stimulation, islets cultured in 2.8 and 11.1 mM glucose released 3% and 5.6% of their total insulin content, respectively. Ultrastructural morphometric analysis indicated that 11.1 mM glucose stimulated an increase in the volume of individual beta-cells, i.e. hypertrophy. The hypertrophy of beta-cells within islets cultured in 11.1 mM glucose resulted in a concomitant increase in islet volume. Finally, the hypertrophy of beta-cells within islets cultured in 11.1 mM glucose was a result of increased volumes of mitochondria, secretory granules, and, to the greatest extent, endoplasmic reticulum. These findings indicate that glucose is a potent factor in the maturation of cultured fetal rat islets.

Multiple effects of growth hormone on insulin release from isolated pancreatic islets

The direct effects of growth hormone (GH) on the endocrine pancreas were studied in isolated islets of rats. To study GH-induced insulin release, islets were incubated in RPMI 1640 medium containing 1 or 10 micrograms/ml of bovine GH for 120 minutes. Islets incubated in the absence of GH served as controls. During the incubation, GH significantly increased the insulin concentration in the medium. To study the effect of GH on subsequent glucose-induced insulin release, islets were preincubated with GH; then the islets were transferred to perifusion chambers and after a 30-minute stabilization period with 2.8 mM glucose, the islets were stimulated by addition of 16.7 mM glucose for 60 minutes. These perifusions were performed in the absence of GH. Glucose-induced insulin release from control and GH-pretreated islets peaked at five minutes during the first phase (0-8 minutes) and plateaued at 25 minutes during the second phase (9-60 minutes). Preincubation with GH (1 microgram/ml) did not change baseline or first phase release, but significantly suppressed the second phase of insulin release. When islets were preincubated with 10 micrograms/ml of GH, both phases of glucose-induced insulin release were suppressed; the total amount of insulin released by GH-pretreated islets was suppressed by 36.6% during the subsequent glucose stimulation period. These data indicate that GH stimulates insulin release by itself (GH-induced insulin release) but inhibits subsequent glucose-induced insulin release in a dose-dependent manner.

Ultrastructural heterogeneity of the mesocoxal muscles of Periplaneta americana

Ultrastructural studies have been performed upon the posterior coxal depressor muscle (136) and a coxal branch of the main depressor group (135d') from the mesocoxa of the cockroach, Periplaneta americana. The quantitative stereometric analyses performed have shown the latter muscle to consist of a dorsal band of fibers having 25.% mitochondria and 13.6% sarcoplasmic reticulum (SR) and T-tubules (TTS), and a ventral group of fibers with only 4.4% mitochondria and 26.6% SR/TTS. The volume fractions characteristic of the ventral fibers of muscle 135d' are also typical of muscle 136.

Enzyme histochemistry of the mesocoxal muscles of Periplaneta americana

Histochemical techniques have been employed to characterize enzymatic activity in the mesocoxal muscles of the cockroach, Periplaneta americana. Through our studies of the enzymes myosin-ATPase, NADH reductase, succinic dehydrogenase (SDH), and lactic dehydrogenase (LDH), we were able to classify fibers within these muscles according to criteria established for muscle fibers of vertebrates. Many of the mesocoxal muscles possess two different and distinct populations of fibers, whereas the remaining muscles are homogeneous with respect to their constituent fibers. The data presented here indicate biochemical heterogeneity for muscles of differing structural and functional features and possible neurotrophic influences upon oxidative enzymes and myosin-ATPase isozymes.

Template activity of liver chromatin increased by in vivo administration of insulin

The hypothesis that insulin may serve as a derepressor of genetic information in the liver of diabetic rats has been tested by comparing the template activity for RNA synthesis of chromatin from liver of insulin-treated diabetic rats to that of chromatin from liver of insulin-deficient diabetic rats. The template activity of the chromatins of insulin-treated diabetic rats is found to be 28 per cent greater than that of chromatin from liver of diabetic rats not treated with insulin. Time course studies show that the template activity of liver chromatin of rats injected with a single dose of insulin reaches a peak at two hours, which is some hours before the appearance of a typical insulin-induced liver enzyme, glucokinase. We conclude that insulin derepresses genetic material of the diabetic liver genome that is repressed in the absence of insulin.

A computer program for immunoassay of protein hormones, with special reference to insulin and growth hormone

A Fortran language program suitable for use in computer processing of two-antibody radioimmunoassay data has been developed. Radioisotope counts transferred to punch-cards are automatically converted to a semilog plot of standard values from which assay values are derived and “printed out” as microunits of insulin and/or milli-micrograms of growth hormone per milliliter of serum or plasma.

Immunoassay of pancreatic and plasma insulin following alloxan injection of rats

Male rats of approximately 200 gm. body weight were injected intravenously with alloxan (40 mg. per kilogram body weight). Blood glucose determinations were carried out at periodic intervals. Plasma samples and acid alcohol extracts of pancreas were assayed by the two antibody method. Five animals were killed at each of the following times: 0, 24, 48, 72 and 96 hrs. The blood glucose concentrations were three times greater than the zero-hour values at each of the latter time periods. In spite of the hyperglycemia at twenty-four hours, there was only a slight decrease in the pancreatic insulin content at this time. Thereafter, the insulin content of pancreatic extracts decreased progressively with time, and at ninety-six hours the insulin concentration was less than 10 per cent of the zero-hour value. The immunoassayable insulin concentration of the plasma did not increase as the pancreatic insulin decreased. These findings suggest that alloxan damaged beta cells did not release their insulin in response to hyperglycemia but that the insulin was destroyed within the beta cell.