Reverse transcriptase from Escherichia coli exists as a complex with msDNA and is able to synthesize double-stranded DNA

Reverse transcriptase required for the synthesis of msDNA.Ec67 in an Escherichia coli strain was purified as a large molecular weight complex with msDNA. The complex sedimented in a glycerol gradient at an s value greater than 19. The predominant protein species co-purifying with reverse transcriptase activity in the complex had a molecular weight estimated at 65,000 which is close to the expected size of 67,227 for the Ec67-reverse transcriptase. In addition, the large complex also contained msDNA.Ec67. The purified complex was able to synthesize cDNA using 5 S rRNA as a template (annealed to a synthetic DNA primer), and a double-stranded DNA using a synthetic DNA template (annealed to a synthetic DNA primer). When msDNA.Ec67 was used as a natural template:primer, the purified complex produced two major products: a 103-base single-stranded DNA by extending the 3' end of msDNA using msdRNA as a template, and a 60-base double-stranded DNA product resulting from the converse reaction in which the 3' end of msdRNA is extended using msDNA as a template. The results suggest that bacterial reverse transcriptase is capable of producing single-stranded cDNA and possibly double-stranded DNA as well. Possible implications of these findings on the biology of the msDNA-retron system are discussed.

Decreased insulin sensitivity in offspring whose parents both have type 2 diabetes

Offspring of two Type 2 diabetic parents have a high prevalence of diabetes and impaired glucose tolerance. Studies in normoglycaemic offspring have shown abnormal insulin responses. Twenty-four non-obese offspring having normal oral glucose tolerance were investigated by the insulin tolerance test for abnormalities of insulin sensitivity. Plasma insulin responses were measured during an oral glucose tolerance test. Although the plasma glucose responses during the OGTT were similar to the control values, the corresponding insulin responses were higher. The mean area under the insulin curve was 121 +/- 29 (+/- SD) mU l-1 h in the control subjects and 203 +/- 73 mU l-1 h in the offspring (p less than 0.001). The mean KITT value in the offspring was 4.3 +/- 1.9 min-1 x 100 which was significantly lower (p less than 0.01) than the value of 6.2 +/- 2.0 min-1 x 100 in the control subjects. The results suggest that some offspring of two Type 2 diabetic parents have low insulin sensitivity and the presence of hyperinsulinism may be a compensatory phenomenon.

Plasma glucagon responses in tropical fibrocalculous pancreatic diabetes

Plasma insulin and glucagon responses to a glucose load were measured in a group of patients with fibrocalculous pancreatic diabetes (FCPD) and compared with patients with noninsulin-dependent diabetes mellitus (NIDDM) and control subjects. Both diabetic groups had markedly diminished insulin responses but the differences between FCPD and NIDDM groups were not significant. In control subjects, in response to the glucose load, plasma glucagon levels decreased while they increased in NIDDM patients. In FCPD patients there was no significant change in glucagon levels in response to the glucose load. The study shows that FCPD patients lack pancreatic alpha-cell responses to a glucose load. This may play a role in protecting these patients against ketosis.

Abnormalities in insulin response to intravenous glucose in offspring of conjugal (type 2) diabetic parents

Glucose and insulin responses were measured during intravenous glucose tolerance test in 12 normal controls and 16 normoglycaemic adult offspring of conjugal diabetic parents. The glucose response curve and the glucose disposal rate in the offspring were not different from the normal pattern. These subjects elicited a lower first phase insulin (0-10 minutes area under the curve, p = 0.04), lower peak immunoreactive insulin response (p = 0.032) and also showed a delay in the first phase (p = 0.037) compared to control values. The second phase of insulin (11-120 minutes area) was not significantly different in the two groups. These changes could serve as early markers of diabetes in offspring of conjugal diabetic parents.

Alterations in brainstem alpha 2 adrenoreceptor activity in pyridoxine-deficient rat model of hypertension

Moderate pyridoxine deficiency in adult male Sprague-Dawley rats results in significant hypertension, associated with a general sympathetic stimulation, including an increase in the turnover of norepinephrine in the heart. Treatment of these rats with pyridoxine reversed blood pressure to normal within 24 h. Treatment of pyridoxine-deficient rats with clonidine or alpha-methyl dihydroxyphenylalanine (alpha-methyl DOPA) also reduced the blood pressure of these animals to normal. There was also a significant increase in the Bmax of high and low affinity [3H]p-amino-clonidine binding to crude synaptosomal membrane preparations of the brain stem of deficient rats indicating chronic underexposure of alpha 2 adrenoreceptors to endogenous norepinephrine.

Development of carbohydrate intolerance in offspring of Asian Indian conjugal type 2 diabetic parents

Sixty-four offspring of conjugal diabetic parents (OCDP) who were normoglycaemic initially were available for a retest after a period of 4-9 years. Among them 10 (15.6%) had developed diabetes, 19 (29.7%) had developed IGT and the remaining 35 (54.7%) had maintained normal GTT. The predictive value of the baseline (initial) parameters was tested. Among the non-obese OCDP (BMI less than 25 and less than 27 for women and men, respectively), the initial sum of plasma glucose (sigma PG), and the mean increment of insulin during GTT (delta IRI), and the 2-h IRI values were higher in the group that developed abnormal glucose tolerance (P less than 0.05 compared to controls and normal OCDP). They also had higher insulin:glucose ratios, indicating higher insulin output for a given glucose concentration. On the other hand, among the obese OCDP the initial parameters did not differ between those who developed abnormal glucose tolerance and those who did not. Stepwise multiple regression analysis showed that the baseline sigma plasma glucose value was significantly related to the final 2-h plasma glucose when all the OCDP were taken together (P = 0.0023) and also in the non-obese OCDP (P = 0.0002). The other parameter which showed a relation to the final 2-h plasma glucose was the baseline delta IRI, although it was not statistically significant (P = 0.08). No such relation was observed in the obese group.

HLA-DP, -DQ and -DR RFLP types in south Indian insulin-dependent diabetes mellitus patients

The frequencies of HLA-DP, DQ and DR RFLP types are compared between insulin-dependent diabetes mellitus (IDDM) patients and healthy controls in the South Indian population. There are no significant differences in the frequencies of any of the DPA. DPB haplotypes, when allowance is made for multiple comparisons. The individual frequencies of two novel alleles, designated "DPA*B" and "DPB*B", however, are significantly higher in controls than in patients, suggesting that these alleles are protective against IDDM. A negative association with DRw15 (DR2). Dw12 is also observed. The positive association with DPw3/6 RFLPs previously observed in White Australians is not present in South Indians. This difference may be due either to undetected heterogeneity within allelic classes or to different linkage disequilibrium patterns between the populations.

Fibrocalculous pancreatic diabetes and obesity

Fibrocalculous pancreatic diabetes (FCPD) is a form of diabetes secondary to chronic pancreatitis that is found in tropical countries. Most patients with FCPD are lean and many are frankly undernourished. Four patients with FCPD who were obese are reported in this paper and this is the first report of obesity in FCPD patients.

Familial aggregation in tropical fibrocalculous pancreatic diabetes

There is very little information on the genetic factors associated with fibrocalculous pancreatic diabetes (FCPD). Ninety-eight first-degree relatives of FCPD patients were subjected to detailed studies, which included glucose tolerance tests, x-ray films of the abdomen, ultrasonography, and studies of exocrine pancreatic function. The study shows that there is a familial aggregation of FCPD with evidence of vertical transmission of the disease from parent to offspring in some families. Routine screening of families of FCPD probands helped to pick up cases in the stage of impaired glucose tolerance. There is heterogeneity in FCPD with respect to familial factors. Some families show marked familial aggregation of FCPD while in others the disease occurs either sporadically or in association with other family members who have abnormal glucose handling.

Testicular function in biotin-deficient adult rats

We have studied testicular function in the biotin-deficient rat biochemically and morphologically. Serum testosterone and luteinizing hormone (LH) levels were decreased significantly in the deficient rats. Administration of biotin or gonadotropins to the deficient rats reversed this decrease in serum testosterone. There was no difference in the serum cholesterol level between the control and biotin-deficient rats. A significant degree of sloughing of seminiferous tubule germinal epithelium was noticed in the biotin-deficient rat testes. Biotin treatment of biotin-deficient rats reversed this condition whereas testosterone treatment was without any effect. The development and maintenance of morphological and functional integrity of the seminiferous tubules appears to require a biotin-mediated step in addition to testosterone.

Two case reports of macrovascular complications in fibrocalculous pancreatic diabetes

Fibrocalculous pancreatic diabetes (FCPD) is a form of diabetes secondary to chronic, non-alcoholic pancreatitis in tropical countries. Being a secondary form of diabetes, vascular complications are believed to be rare. In this paper we present two case reports of macrovascular complications (myocardial infarction and gangrene). This shows that large vessel disease does occur in FCPD.

Myxococcus xanthus msDNA.Mx162 exists as a complex with proteins

Myxococcus xanthus, a myxobacterium, contains a peculiar branched RNA-linked DNA called msDNA. Reverse transcriptase has been shown to be required for the production of msDNA. Existence of proteins that bind to one of the two msDNAs in M. xanthus, msDNA.Mx162, was examined by gel retardation assays. Total cell-free extract yielded two distinct retarded bands. Both bands were sensitive to treatment with proteinase K, indicating that there is a protein(s) that is able to bind to msDNA. Further, the formation of the bands was inhibited by the addition of nonradioactive msDNA but not by a large excess of poly(dA) in the presence of a 5000-fold excess of poly(dI.dC).poly(dI.dC). In vivo footprinting using dimethyl sulfate revealed that the deoxynucleotide stretch from 60 to 161 is protected. When a M. xanthus cell lysate was centrifuged in a 16-30% glycerol gradient, msDNA was found to sediment in two peaks: a major peak corresponding in size to 14 S, and a minor one at 5 S. These results indicate that msDNA.Mx162 exists as a complex with specific proteins in the cell.

Thermal and metabolic responses to cold by men and by eumenorrheic and amenorrheic women

Previous work has suggested that men (M) are more sensitive to cold stress than women. There have also been observations that suggest that amenorrheic women (AW) are less thermally responsive than eumenorrheic women (EW). We investigated the hypothesis that M, EW, and AW would have different responses to cold stress. The subjects (6/group) were tested four times: twice at rest for 60 min (5 and 22 degrees C) and twice in a progressive exercise test (5 and 22 degrees C). At rest at 22 degrees C AW had a lower O2 uptake (VO2) than M and lower rectal (Tre) and finger temperatures than EW. At rest at 5 degrees C both AW and EW had lower skin temperature (Tsk) than M, but there were no group differences in peripheral Tsk sites. M increased VO2 after 10 min and EW after 20 min of cold stress; however, AW did not increase metabolism until 60 min. In the two exercise tests Tre increased in proportion to relative work load; in the 5 degrees C test there was little evidence that exercise increased Tsk sites above rest levels. Few of the metabolic or thermal differences could be accounted for by body fatness, body surface area (BSA), or BSA/kg. The data support the hypothesis that M, EW, and AW have different responses to cold stress.

Retinopathy in insulin dependent diabetes mellitus (IDDM) in south India

The prevalence of diabetic retinopathy was assessed by direct and indirect ophthalmoscopy in a group of patients with insulin dependent diabetes mellitus (IDDM). Fourteen percent of patients had retinopathy. Proliferative retinopathy and severe background retinopathy including maculopathy were both seen in four percent of patients. It is possible that the lower prevalence rates for these complications is due to the shorter duration of diabetes in our patients.

Fibrocalculous pancreatic diabetes in the elderly

Fibrocalculous pancreatic diabetes (FCPD) is a form of diabetes seen in tropical countries. It is secondary to chronic, calcific, non-alcoholic pancreatitis. FCPD is usually a disease of youth. This paper reports on two elderly onset cases of FCPD. Macrovascular complications are usually rare in FCPD patients. These two patients had evidence of macrovascular diseases probably due to the older age group of the patients.

Decreased insulin binding in Asian Indian women with gestational diabetes mellitus

Insulin binding to erythrocyte insulin receptors was studied in 10 women with gestational diabetes and compared with 10 matched, normal, pregnant women and 10 normal, non-pregnant controls, with no family history of diabetes. Pregnant women had higher mean fasting and post-glucose plasma immunoreactive insulin (IRI) compared to non-pregnant controls (p less than 0.001). Women with gestational diabetes had higher mean fasting and post-glucose plasma glucose levels and a lower mean specific binding of insulin when compared with the other two groups (p less than 0.001). The decreased insulin binding was significant only at lower insulin concentrations (0.2-2 ng/ml) when compared with those of normal pregnant women (p less than 0.01), suggesting decreased receptor affinity with no change in receptor number. In addition, an increased mean ED50 value for 50% inhibition of maximal binding and a lower mean average affinity constant Ke (empty site) obtained in gestational diabetes in comparison to the other two groups also suggested de decreased affinity of the receptor. The finding that pregnancy with normal glucose tolerance was not accompanied by changes in insulin binding against decreased insulin binding and affinity observed in gestational diabetes suggested a pathogenetic role for impaired insulin binding as one of the factors responsible for insulin resistance and hyperglycemia in gestational diabetes.

Exocrine pancreatic function in tropical fibrocalculous pancreatic diabetes

Exocrine pancreatic function was studied by fecal chymotrypsin test in three groups of diabetic patients seen in southern India. Exocrine pancreatic insufficiency, as shown by low fecal chymotrypsin levels, was seen in 87.5% of patients with fibrocalculous pancreatic diabetes (FCPD), in 23.5% of insulin-dependent diabetes mellitus patients, and in 4.5% of non-insulin-dependent diabetes mellitus patients. There was no correlation between fecal chymotrypsin levels and serum amylase, serum lipase, age, body mass index, duration of diabetes, fasting plasma glucose, or glycosylated hemoglobin levels. The fecal chymotrypsin test is a useful additional investigation for the diagnosis of FCPD found in tropical countries.

The genetic predisposition to fibrocalculous pancreatic diabetes

Fibrocalculous pancreatic diabetes (previously known as tropical pancreatic diabetes) is a rare cause of diabetes confined to countries within the tropical belt. The aetiology of fibrocalculous pancreatic diabetes is thought to be environmental although the agent(s) is unknown. We have investigated a possible genetic basis of this disease by looking for restriction fragment length polymorphisms of genes implicated in the aetiology of diabetes mellitus. Seventy-six Dravidian patients with fibrocalculous pancreatic diabetes were studied, and the restriction fragment length polymorphisms obtained compared to racially matched control subjects (n = 94), patients with Type 2 (non-insulin-dependent) diabetes (n = 87) and Type 1 (insulin-dependent) diabetes (n = 58). No association of fibrocalculous pancreatic diabetes was found with restriction fragment length polymorphisms of the insulin receptor gene. Although no association of fibrocalculous pancreatic diabetes was found with polymorphism of the HLA DR alpha/DQ alpha/DX alpha genes, an association was found with the Taq 1 restriction fragment length polymorphisms of the DQ beta gene (DQ beta T2/T6 present in 39% of patients with fibrocalculous pancreatic diabetes compared to 19% in control subjects; p = 0.01; corrected p value = 0.04) which is similar to that found in Type 1 but not Type 2 diabetes. An association of fibrocalculous pancreatic diabetes was also found with the hypervariable region in the 5-prime flanking region of the insulin gene; 40% of patients possessed the class 3 allele compared to 9.5% of control subjects p = 0.0001; corrected p value = 0.0008).(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin resistance in Fibrocalculous (tropical) pancreatic diabetes

Insulin resistance was assessed by Insulin Tolerance Test (ITT) in 12 patients with FCPD, 10 with NIDDM and 12 age and sex matched control subjects. The mean BMI of the FCPD was lower than the NIDDM and control groups (P less than 0.001). There was no significant difference between the mean fasting plasma glucose or HbA1 between the FCPD and NIDDM patients. The mean fasting C-peptide of the FCPD group was significantly lower than the NIDDM and control groups (P less than 0.001). The mean glucose disposal rate (KITT) was 5.57 +/- 2.28 in the control group, 2.15 +/- 2.00 in the FCPD and 1.77 +/- 0.91 in the NiDDM group (P less than 0.001, control vs FCPD and NIDDM). The difference in KITT between FCPD and NIDDM groups was not significant statistically. The data suggests that patients with FCPD have evidence of insulin resistance and this is similar to that seen in NIDDM patients.