Chandan Prasad

Alterations in hypothalamic-pituitary-thyroid regulation produced by diabetes mellitus

Abstract Studies concerning thyroid regulation have been performed in male rats rendered experimentally diabetic with streptozocin (65 mg/kilo i.p.). The induction of diabetes was attended by hyperglycemia (mean blood glucose − 378 ± 49 mg/dl) and impaired somatic growth after 72–96 hours. A number of thyroidal abnormalities were identified, including reductions in circulating T 4 , T 3 , and TSH. These falls in thyroid hormone concentrations could not be ascribed to altered serum protein binding. The diminution of TSH was found to be associated with a significant reduction in peripheral blood TRH concentrations (26 ± 4 pg/ml in diabetics vs. normals of 48 ± 3 pg/ml, N = 9, p .02) measured following extraction with 0.2 M Ba (OH) 2 and 5% ZnSO 4 , and concentration by anti-TRH IgG affinity chromatography. The lowering of TRH concentrations appears to be the principal determinant of the reduced performance of the pituitary-thyroid axis, since TRH binding capacities of pituitary plasma membranes were not lower than normal in diabetics. It is concluded that diabetes mellitus is associated with a downward re-setting of the hypothalamic-pituitary-thyroid axis.

Radioimmunoassay of cyclo (HIS-PRO) in unextracted human plasma: report of a normal range and definition of factors critical for successful assay

A radioimmunoassay for cyclo(His-Pro) (CHP) in unextracted human plasma that can detect 40 pg has been developed. Elution profile of CHP-like immunoreactivity (CHP-LI) corresponded precisely to those of [3H] cyclo(His-Pro) by both high pressure liquid chromatography and Sephadex G-25 column chromatography. In addition plasma CHP-LI exhibited close immunoidentity with authentic CHP. Charcoal treatment of plasma containing [3H] cyclo(His-Pro) resulted in loss of both CHP-LI and [3H] cyclo(His-Pro) activity. Plasma frozen at draw and assayed at 0, 6 and 24 hours displayed no change in CHP-LI while an aliquot from the same sample maintained at 4 degrees C and assayed at the same time intervals showed a 50% rise (0 hrs-856 +/- 47 pg/ml; 24 hrs-1288 +/- 85 pg/ml) (+/- SE) over 24 hours. In addition, plasma drawn from 14 volunteers and immediately frozen until assay yielded a mean CHP value of 829 +/- 64 pg/ml (+/- SE) while that of 14 volunteers that was maintained at 25 degrees C for 90 minutes was significantly higher at 1085 +/- 34 pg/ml (+/- SE) (p less than 0.03). Taken together, these data suggest that CHP can be easily measured in a direct RIA of human plasma, however, failure to maintain the sample frozen from the time of draw until assay may yield spuriously elevated values.

A paradoxical elevation of brain cyclo(His-Pro) levels in hyperphagic obese Zucker rats

Several studies suggest a role for endogenous cyclo(His-Pro) or CHP in appetite regulation. In the present study, we have examined the regional brain distribution of CHP in hyperphagic obese Zucker rats and their lean littermates. The data show a significant elevation in the levels of CHP in many brain regions, including hypothalamus of the obese rat. Within the hypothalamus, the lateral hypothalamic (LH) nucleus of obese rats had significantly higher levels of CHP when compared to that of the lean littermates. Administration of dehydroepiandrosterone, a steroid hormone known to decrease food intake and body weight gain, to obese rats led to decrease in the levels of CHP in the LH. These data further suggest a role for the endogenous CHP in attenuating food intake.

Identification and characterization of cyclo(His-Pro)-like immunoreactivity in amniotic fluid.

Amniotic fluid (AF) from 25 term pregnancies was analyzed for cyclo(His-Pro)-like immunoreactivity (CHP-LI). CHP-LI was detected in all AF samples and was indistinguishable from synthetic CHP by immunoidentity, by gel chromatography on Sephadex G-25, and by high pressure liquid chromatography. The mean concentration of CHP-LI in AF was 13,622 +/- 1288 pg/ml (+/- SE) and concentrations were not altered by maternal labor. Plasma concentrations of CHP-LI were similar in 4 pregnant and 4 control subjects [2260 +/- 432 pg/ml vs. 2162 +/- 419 pg/ml (+/- SE), respectively]. We conclude that 1) CHP-LI is readily detected in AF from term pregnancies and is indistinguishable from synthetic CHP, and 2) concentrations of CHP-LI in human AF are significantly higher than concentrations of maternal plasma CHP-LI, suggesting CHP AF originates by mechanisms other than diffusion from maternal plasma.

Azaftig, a urinary proteoglycan from a cachectic cancer patient, causes profound weight loss in mice

Cachexia is a complex medical condition characterized by significant weight loss associated with decreased body fat and protein; the condition may present itself with or without anorexia. We have isolated and partially characterized a proteoglycan (azaftig) from the urine of cancer and AIDS patients experiencing weight loss. When given to mice, the purified azaftig resulted in a significant decrease in body weight and body fat without any effect on appetite. The results of these studies show that azaftig may be one of the many factors participating in the emergence of the cachectic state.

Optimization of conditions for the simultaneous separation of ten tryptophan metabolites using reversed-phase high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method for the separation of tryptophan and ten metabolites of tryptophan pyrrolase pathway has been developed by sequential optimization of mobile phase, by adjusting the pH, the concentration of triethylamine and the gradient elution. The baseline resolution of the compounds, by this optimized procedure, is obtained with an analysis time, including the re-equilibration period, of less than 30 min. We believe this is the first RP-HPLC method that can separate tryptophan and ten of its metabolites in a single chromatographic run.

CYCLO(HIS-PRO) AUGMENTS THE INSULIN RESPONSE TO ORAL GLUCOSE IN RATS

Cyclo(His-Pro) (CHP) is a gut-brain peptide found in rat and man. Since plasma levels of CHP are altered by oral glucose ingestion, we wondered whether exogenous CHP might alter the insulin response to oral glucose ingestion. To this end, rats were given 3g/kg oral glucose load with either saline or increasing doses of CHP and plasma levels of insulin, C-peptide and glucose were measured. We found mean insulin but not C-peptide excursions and area under the insulin but not C-peptide response curves (AUC) were significantly higher in the CHP groups than controls despite similar glucose responses. In summary, these data show that in rats receiving oral glucose, CHP causes higher insulin excursions without any change in C-peptide suggesting that CHP may decrease hepatic insulin clearance.

The neuropeptide histidyl proline diketopiperazine throughout human pregnancy: An inverse correlation with amniotic fluid prolactin

Histidyl proline diketopiperazine values have been established in human amniotic fluid (n = 81) and maternal serum (n = 36) throughout gestation (10 to 42 weeks). Newborn cord serum (n = 10) and first-voided fetal urine (n = 10) levels were also documented. These measurements reveal increasing amniotic fluid levels with term gestation values (15,551 pg/ml) nearly thirteen-fold higher than maternal serum concentrations (1150 pg/ml). Corresponding fetal urine and cord serum concentrations were 16,781 and 2160 pg/ml, respectively. The amniotic fluid values are not influenced by fetal sex or maternal labor, nor do they correlate with amniotic fluid alpha-fetoprotein levels. However, there is a significant inverse correlation (r = -0.628; p less than 0.0001) between amniotic fluid prolactin and histidyl proline diketopiperazine after midgestation. The hypothesis that histidyl proline diketopiperazine may be a regulatory peptide for decidual prolactin production was tested by culturing term decidua in the presence of varying concentrations of histidyl proline diketopiperazine, but no inhibitory effect was observed. Decidual cultures did not produce measurable amounts of histidyl proline diketopiperazine. It is suggested that amniotic fluid histidyl proline diketopiperazine is derived from fetal urine.

Tart cherry in amelioration of pain in the elderly

BACKGROUND: Tart cherry, rich in bioactive polyphenols, has received attention in the past decade for reported health benefits due to its high polyphenolic content. OBJECTIVE: To determine whether there is a potential role for tart cherry or its isolated components in amelioration of pain relief in chronic diseases that may affect the elderly. METHODS: In vitro and in vivo human and animal studies that utilized tart cherry or extracts of tart cherry compounds to determine an effect on oxidative stress, inflammation, muscle damage, and pain were reviewed and summarized (Table 1). RESULTS: Tart cherry and its isolated compounds have demonstrated antioxidant and anti-inflammatory effects both in vitro and in vivo which may improve self-reported pain. In humans, these include modest improvements in gout flare incidents, and self-reported pain in fibromyalgia, osteoarthritis (OA), and conditions of induced oxidative stress and muscle damage. Beneficial biochemical changes were also reported for inflammatory and oxidative biomarkers such as serum urate, C-reactive protein (CRP), and interleukin-6 (IL-6). However, most studies reported to date have insufficient sample size, treatment duration, and statistical power to draw any firm conclusions. CONCLUSIONS:Consumption of tart cherries and their bioactive constituents may be a potential novel therapy for reducing the pain associated with chronic diseases particularly common to an aged population. Larger, more rigorous trials are needed to reach any firm conclusions.

The Neuropeptide Cyclo(His-Pro) Levels are Increased in Diabetic Ketoacidosis and Fall with Treatment in Parallel with Levels of Glucagon

The importance of insulin deficiency and glucagon excess is recognized as critical in the pathogenesis of diabetic ketoacidosis (DKA). The finding of elevated levels of another gut peptide in DKA with potential relevant physiological effects might renew discussion of the pathogenesis of this disorder. Cyclo(His-Pro) is a gut-brain peptide found in gut of rat and man. In pancreas it is localized to alpha cells. A stereospecific hepatic bonding site has been found. We have shown that cyclo(His-Pro) augments the insulin response to oral glucose in rat by decreasing hepatic insulin clearance. In view of cyclo(His-Pro)s location in alpha cells, the hepatic binding site and action described, we wondered if levels of cyclo(His-Pro) might be elevated in a hyperglucagonemic state such as DKA and whether these levels might correlate with those of glucagon and other commonly followed parameters in DKA. Plasma was collected from 7 nondiabetic controls and 9 patients in DKA before and after 4, 8, 12, and 24 h of therapy and assayed for glucose, HCO3, anion gap, glucagon and cyclo(His-Pro). Cyclo(His-Pro) levels were higher in DKA patients before therapy than controls (15.6 ± 3.2 vs. 8.0 ± 0.2 pmol/ml; p =0.023) as were glucagon levels (201 ± 4 vs. 56 ± 5ng/L; p = 0.006). Cyclo(His-Pro) levels fell significantly with treatment (15.6 ± 3.2 vs 8.1 ± 1.1; p = 0.024) and in parallel with those of glucagon. We conclude that cyclo(His-Pro) levels are increased in patients with DKA before therapy and fall in parallel with those of glucagon. This represents the first report of altered levels of this peptide in a disease state.