Molecular and functional characterization of amylin, a peptide associated with type 2 diabetes mellitus

The 37-amino acid peptide called amylin is a major component of the islet amyloid deposited in the pancreases of persons with type 2 diabetes mellitus. We report the isolation of a partial cDNA clone and a phage lambda genomic clone of the coding region of the amylin gene. The DNA sequence encodes a protein sequence identical to that of amylin isolated from the amyloid found in the diabetic pancreas and shows that amylin is likely to be synthesized as a precursor peptide, now named proamylin. We have demonstrated that the amylin gene is present on chromosome 12 and that it is probably transcribed in the islets of Langerhans. The sequences of the genes for amylin and the calcitonin gene-related peptides (CGRPs) show strong similarity, especially over their 5' coding regions, where both peptides have a conserved intramolecular disulfide bridge, and also over their 3' coding regions, where the presence of a glycine codon strongly suggests that the carboxyl-terminal residue of amylin, like that of CGRP, is amidated. To examine the functional relevance of these posttranslational modifications, the biological activity of amylin synthesized with or without the disulfide bridge and/or amidation was measured. It was found that both features are necessary for full biological activity, thereby confirming the functional importance of those regions of the molecule whose sequences are conserved at both protein and genetic levels.

Digitalislike immunoreactive substances and extracellular fluid volume status in chronic hemodialysis patients

Circulating digitalislike immunoreactive substances (DLIS) may represent a class of volume-sensitive natriuretic factors. Chronic renal failure patients are known to have elevated levels of circulating natriuretic activity and also to have detectable DLIS. Using digoxin radioimmunoassay, DLIS levels were measured in desalted, deproteinized plasma from 15 stable hemodialysis patients. Predialysis DLIS was 109.3 +/- 6.3 pg/mL (digoxin equivalents) and decreased to 97.5 +/- 5.9 pg/mL following dialysis (P less than 0.001). Predialysis DLIS correlated with weight gain from the prior dialysis (P less than 0.01). The degree of extracellular fluid volume expansion predialysis also correlated with predialysis DLIS (P less than 0.01). Postdialysis DLIS also correlated with postdialysis extracellular fluid volume status (P less than 0.01). DLIS levels in dialysis patients were higher than in 50 normal subjects (30.0 +/- 1.2 pg/mL; P less than 0.001). Also, the changes in DLIS with dialysis were paralleled by similar changes in simultaneously measured human alpha-atrial natriuretic peptide (ANP) levels. These results demonstrate that (1) DLIS levels are higher in hemodialysis patients than in normal individuals; (2) with dialysis, DLIS levels increase and decrease in association with extracellular fluid volume expansion and removal, respectively; (3) DLIS levels correlate with the degree of extracellular fluid volume expansion in dialysis patients; and (4) DLIS levels change in parallel with levels of another class of natriuretic factor ANP. These characteristics are consistent with the hypothesis that DLIS represents a volume-sensitive factor.

Increased plasma PGE2, 6-keto-PGF1 alpha, and 12-HETE levels following experimental concussive brain injury

Previous investigations have shown that brain prostaglandin levels are transiently elevated following experimental fluid percussion brain injury. Associated with these increased prostaglandin levels there is free radical production and abnormalities in cerebral arteriolar function. The purpose of this study was to determine whether experimental fluid percussion brain injury in cats is associated with increased systemic levels of prostaglandins and the lipoxygenase product, 12-HETE. Blood samples were collected before and at various periods of time after 2.7 atm of fluid percussion brain injury was produced in adult cats. Prostaglandin and 12-HETE analysis was performed by radioimmunoassay after extraction of the plasma samples. The control levels for 6-keto-PGF1 alpha, PGE2, and 12-HETE were 477 +/- 42, 2,372 +/- 431, and 13,328 +/- 1,769 pg/ml, respectively. Following injury all three eicosanoids reached peak plasma levels by 1-5 min after injury. The percentile increases for all eicosanoids were similar and increased from 70 to 110%. The increases were sustained at up to 30 min postinjury and by 1 h after injury were at control levels. As in previous studies, hypertension following injury was maximal by 1 min postinjury and blood pressure had returned to near normal levels by 5 min postinjury. These studies demonstrate prolonged systemic increases in eicosanoids following injury. Since free radical production and vascular damage occur concomitantly with eicosanoid production, the prolonged increases in these products suggest that there is an attainable therapeutic window following injury during which administration of free radical scavengers may decrease radical damage and reduce the consequences of injury.

A randomised controlled trial of adjuvant hormono-chemotherapy in Stage II breast cancer

From 1979 to 1984 women with histologically proven Stage II breast cancer were entered into a randomised controlled trial of adjuvant hormono-chemotherapy following mastectomy. Adjuvant therapy was started within 2 weeks of surgery and was given for 6 months as continuous 'Tamoxifen' and 6-monthly cycles of vincristine, adriamycin and cyclophosphamide (VAC). Of the 157 women randomised 82 were assigned to the control group and 75 to the adjuvant group. Comparing the two groups by life table analysis the rate of recurrence was found to be significantly greater in the control group (n = 46) than in the adjuvant group (n = 25) (Peto log rank test chi 2 = 7.46 P less than 0.01). Although there were more deaths amongst the control patients (n = 31) than in those randomised to receive adjuvant therapy (n = 18), this difference did not achieve statistical significance (chi 2 = 2.80 P less than 0.1). This analysis has shown that although adjuvant hormono-chemotherapy may significantly delay recurrence the trial has failed to demonstrate any significant improvement in the survival of women with Stage II breast cancer following mastectomy.

Endometriosis and the gut

Six patients with endometriosis involving the intestine are described and illustrate the variety of symptoms which may occur in this condition, many of which are frequently associated with the more common gastrointestinal illnesses. A correct preoperative diagnosis based on history, clinical examination, radiology, and endoscopy may be difficult to make, and when first discovered at laparotomy endometriosis can easily be mistaken for other inflammatory, or neoplastic processes. A histological diagnosis should always be made before definitive treatment.

Effect of hypophysectomy on energy balance and brown fat activity in obese Zucker rats

Hypophysectomy (HYPX) in genetically obese (fa/fa) Zucker rats significantly reduced body weight and energy gains and stimulated energy expenditure (by 34%), the thermic response to food (by 144%), and brown adipose tissue (BAT) mitochondrial GDP-binding capacity (by 190%) compared with pair-fed, sham-operated obese rats. These changes in energy balance in obese HYPX rats were reversed by corticosterone replacement (1 mg/day), but the increased BAT activity was only partly restored to normal. HYPX had only small effects on energy balance in lean Zucker rats compared with pair-fed, sham-operated lean controls but increased the acute thermic response to food and BAT mitochondrial GDP-binding capacity; these effects were inhibited by replacement of HYPX rats with corticosterone. The results suggest that alterations in the hypothalamic-pituitary-adrenal axis play a fundamental role in the development and maintenance of genetic obesity.

Mapping of 12 translocation breakpoints in the Xp21 region with respect to the locus for Duchenne muscular dystrophy

Over 20 females have been reported to carry reciprocal X; autosome translocations with breakpoints in Xp21 and to suffer from Duchenne muscular dystrophy (DMD). We have positioned nine of these breakpoints with respect to the Duchenne gene by mapping probes from the DMD region against a panel of somatic cell hybrids, each containing one of the translocation chromosomes from a different female patient; further information has also been obtained by in situ hybridization, including the breakpoint location in a tenth DMD patient. We have also characterized two translocation breakpoints that lie in the same chromosomal region but which are not associated with the expression of DMD. All the DMD-associated translocation breakpoints examined lie at several sites within the DMD locus and between the two non-DMD breakpoints.

Brain 12-HETE formation in different species, brain regions, and in brain microvessels

We used gas chromatography/mass spectrometry to measure brain 12-HETE (12-Hydroxy-5,8,10,14-eicosatetraenoic acid) formation from endogenous arachidonic acid in different species and different brain regions and in isolated brain microvessels. When blood-free brain slices were incubated for 20 minutes we found that the rabbit and cat brain incubates contained little 12-HETE when compared to rat and mouse brain incubates. Further in vitro studies of various rat brain regions showed a generally even distribution of 12-HETE. When isolated rat or rabbit microvessels were incubated and analyzed, we found 1 and 0.25 micrograms, respectively, of 12-HETE/mg of microvessel protein. Also, rabbit brain had limited or no capacity to actively metabolize tritiated 12-HETE. In summary, these studies show substantial species variation with respect to brain formation of 12-HETE and indicate that the vasculature is a potentially significant contributor to the 12-HETE found in whole brain tissue.

Gastric enzymes as a screening test for gastric cancer

Levels of lactic dehydrogenase and beta-glucuronidase were measured in gastric wash samples obtained from 445 patients over 40 years old attending a routine diagnostic endoscopy clinic. An index was derived from the two levels and used as a test for the presence of gastric cancer. Of the 24 patients with an endoscopic diagnosis of gastric cancer, 21 (91.3%) proved positive on this test, including all four cases of early gastric cancer, which were found at repeat endoscopy. The specificity of the test for gastric cancer was 81.3%. Among those patients with false positive results who had endoscopic biopsy were four out of the five cases of severe dysplasia, and four out of the 13 cases of type 2B intestinal metaplasia. Atrophic gastritis alone or with intestinal metaplasia was found in 95.9% of the false positives who were biopsied.

Muscular dystrophy in girls with X;autosome translocations

Twenty known cases of X;autosome translocations with breakpoints at Xp21 associated with Duchenne or Becker muscular dystrophy in girls are reviewed. The variable severity described for different persons may reflect differences in X inactivation or in the nature of the genomic target disrupted. High resolution cytogenetic studies on 12 cases indicate breakpoints on the X chromosome at Xp21.1 or Xp21.2. Translocation chromosomes from several of these cases have been isolated in human/mouse somatic cell hybrids. Molecular heterogeneity in the breakpoint positions has been established by probing DNA from these hybrids with a range of cloned sequences known to be located within, or closely linked to, the Duchenne region. The minimum separation between the most distal and the most proximal breakpoints is 176 kb suggesting that, if a single gene is involved, it must be large. Alternatively, the translocations may affect different genes, or confer alterations to regulatory sequences which operate at a distance.

Myocardial tissue iron delocalization and evidence for lipid peroxidation after two hours of ischemia

Ischemic tissue injury has been proposed to be in part due to oxygen-radical-mediated lipid peroxidation. In vitro studies of such reactions show that they are thermodynamically unfavorable unless catalyzed by transitional metals such as iron in low molecular weight species (LMWS iron), ie, the iron-ADP complex. This study tests for iron delocalization into a LMWS pool during myocardial ischemia and for increased tissue malondialdehyde (MDA), a product of lipid peroxidation. Anesthesia was induced in eight dogs (weighing 20 to 30 kg) with ketamine and maintained by ventilation with 1% halothane. The left anterior descending coronary artery was ligated in four animals, and the circumflex coronary artery was ligated in the other four. Two hours after ligation, the animals were sacrificed by a central venous injection of KCl. Tissue samples were immediately taken from the ischemic zone and from the corresponding nonischemic zone. MDA was determined by the thiobarbituric acid assay. LMWS iron was determined on a tissue ultrafiltrate by the o-phenanthroline assay. Statistical data analysis used the matched-pair two-tailed t test. LMWS iron was 18.3 nM/100 mg in ischemic tissue versus 13.1 nM/100 mg in nonischemic tissue (t = 4.14; P less than .01). MDA was 0.91 nM/100 mg in ischemic tissue versus 0.83 nM/100 mg in nonischemic tissue (t = 7.27; P less than .005). We conclude that there is a significant increase in tissue LMWS iron and in MDA after two hours of regional myocardial ischemia. This iron might be the catalyst for maturation of tissue injury during reperfusion as observed by other investigators.(ABSTRACT TRUNCATED AT 250 WORDS)

Is gastric emptying abnormal in duodenal ulcer?

To investigate the possibility that an abnormality of gastric emptying exists in duodenal ulcer and to determine if such an abnormality persists after ulcer healing, scintigraphic gastric emptying measurements were undertaken in 16 duodenal ulcer patients before, during, and after therapy with cimetidine; in 12 patients with pernicious anemia, and in 12 control subjects. No difference was detected in the rate or pattern of gastric emptying in duodenal ulcer patients before and after ulcer healing with cimetidine compared with controls, but emptying of the solid component of the test meal was more rapid during treatment with the drug. Comparison of emptying patterns obtained in duodenal ulcer subjects during and after cimetidine treatment with those obtained in pernicious anemia patients and controls revealed a similar relationship that was characterized by a tendency for reduction in the normal differentiation between the emptying of solid and liquid from the stomach. The similarity in emptying patterns in these groups of subjects suggests that gastric emptying of solids may be influenced by changes in the volume of gastric secretion. The failure to detect an abnormality of gastric emptying in duodenal ulcer subjects before and after ulcer healing calls into question the widespread belief that abnormally rapid gastric emptying is a feature with pathogenetic significance in duodenal ulcer disease.

Clinical versus laboratory detection of alcohol abuse: the alcohol clinical index

To determine reliable indicators of alcohol abuse a comprehensive set of clinical and laboratory information was acquired from three groups of subjects with a wide range of drinking histories: 131 outpatients with alcohol problems, 131 social drinkers, and 52 patients from family practice. Findings from clinical examination provided greater diagnostic accuracy than laboratory tests for detecting alcohol abuse. Logistic regression analysis produced an overall accuracy of 85-91% for clinical signs, 84-88% for items from the medical history, and 71-83% for laboratory tests in differentiating the three groups. Further analyses showed 17 clinical signs and 13 medical history items that formed a highly diagnostic instrument (alcohol clinical index) that could be used in clinical practice. A probability of alcohol abuse exceeding 0.90 was found if four or more clinical signs or four or more medical history items from the index were present. Despite recent emphasis on the laboratory diagnosis of alcohol abuse simple clinical measures seem to provide better diagnostic accuracy.

Food allergy or intolerance in severe recurrent aphthous ulceration of the mouth

Images

Measurement of gastric emptying rate in humans by real-time ultrasound

Simultaneous studies of gastric emptying by ultrasound and scintigraphy were performed in 14 subjects to assess the use of ultrasound for the measurement of gastric emptying rate. The presence of air in the stomach prevented the acquisition of gastric emptying data by ultrasound in 3 of the 14 subjects. In the remaining 11 subjects there was no significant difference between values for the half-time (t1/2) of gastric emptying obtained by scintigraphy [for anterior imaging, mean t1/2 = 20.9 +/- 9.9 min (+/- SD); for anterior and posterior imaging, geometric mean t1/2 = 21.1 +/- 10.5 min (+/- SD)] compared with those derived by ultrasound [mean t1/2 = 20.2 +/- 10.0 min (+/- SD), p greater than 0.05 for each comparison]. A significant correlation between the t1/2 of gastric emptying derived by scintigraphy (anterior scanning and geometric mean of counts obtained by anterior and posterior scanning) and the t1/2 measured by ultrasound was obtained (r2 = 0.7, 0.69, respectively). These results imply that ultrasound can be used for the valid assessment of the gastric emptying rate in humans.

In vitro thymidine labelling index in primary operable breast cancer

The in vitro Thymidine Labelling Index (TLI) of 164 primary breast carcinoma was measured. The relationship of TLI to other established prognostic variables was examined, and the rates of of recurrence and survival of groups of women with high and low TLI tumours were compared. Poorly differentiated tumours had significantly greater TLI values but there were no significant associations with tumour size, axillary lymph node status, age and menopausal status or steroid receptor status. Although there were more recurrences and deaths in the group of women with high TLI tumours, these differences were not statistically significant. In vitro TLI may be a further expression of tumour differentiation, rather than cellular proliferation, and from this study does not provide any additional prognostic information.