Diabetic hepatosclerosis: another diabetes microvascular complication?

BACKGROUND: Liver disease in diabetes is common and is frequently the result of hepatic steatosis. Diabetic hepatosclerosis is a relatively recent description of sinusoidal fibrosis, without steatosis, observed in liver biopsies of people with diabetes presenting with cholestasis. Its association with other microvascular complications suggests it is a form of hepatic diabetic microangiopathy. CASE REPORT: We report the case of a 50-year-old woman with longstanding Type 1 diabetes, complicated by nephropathy resulting in cadaveric renal transplant, retinopathy, gastroparesis and neuropathy with slowly healing ulceration to her right foot. She was noted to have deranged liver function tests: alanine aminotransferase, 162 IU/l; bilirubin, 44 IU/l; alkaline phosphatase, 5279 IU/l (isoenzymes; bone 1029 IU/l, liver 4250 IU/l); γ-glutamyl transferase, 662 IU/l. A non-invasive liver screen did not reveal the cause of the cholestasis. A liver biopsy demonstrated sinusoidal fibrosis without evidence of steatosis and thus a diagnosis of diabetic hepatosclerosis was made. Comparison with a biopsy performed 11 years previously at a different trust due to elevated alkaline phosphatase levels revealed slow progression of the sinusoidal fibrosis. DISCUSSION: This case describes the longest reported clinical course of diabetic hepatosclerosis, spanning 11 years, in which time the patient did not develop evidence of cirrhosis or portal hypertension. It is difficult to estimate the clinical relevance of this condition because little is known regarding its clinical course and effect on morbidity and mortality. Identified patients should undergo low-intensity, long-term follow-up to improve understanding of its clinical sequelae and relevance.

Disparity of autonomic control in type 2 diabetes mellitus.

AIMS/HYPOTHESIS: Acute insulinaemia activates the sympathetic drive in a nonuniform manner. The extent and nature of such activation in type 2 diabetic patients who do not have neuropathy have not yet been addressed despite evidence relating sympathetic activation to cardiovascular risk. We planned to determine the magnitude and extent of the sympathetic drive and its reflex responses in patients with type 2 diabetes and fasting hyperinsulinaemia. METHODS: We measured resting muscle sympathetic nerve activity (MSNA) as the mean frequency of multi-unit bursts and single unit muscle sympathetic nerve activity (s-MSNA) in 17 overweight patients with type 2 diabetes and two matched normal control groups comprising 17 overweight and 16 normal-weight subjects. We also tested the MSNA and s-MSNA responses to cold pressor and isometric hand-grip tests, along with the effect of sympatho-vagal balance on heart period variability. RESULTS: Both MSNA and s-MSNA in the group with type 2 diabetes (66+/-3.5 bursts/100 beats and 78+/-4.5 impulses/100 beats) were greater (at least p<0.0001) than in the overweight control group (42+/-2.6 bursts/100 beats and 48+/-3.4 impulses/100 beats) and normal-weight control group (43+/-6.2 bursts/100 beats and 51+/-7.1 impulses/100 beats), though the three groups had similar reflex responses, baroreflex sensitivity and sympatho-vagal balance controlling the heart period. CONCLUSIONS/INTERPRETATION: The patients with type 2 diabetes had no evidence of impaired reflex or autonomic control of heart period variability at a time when there was central sympathetic activation to the periphery. Furthermore, being overweight itself was not associated with sympathetic activation.

Water ingestion increases sympathetic vasoconstrictor discharge in normal human subjects.

A marked pressor response to water drinking has been observed in patients with autonomic failure and in the elderly, and has been attributed to sympathetic vasoconstrictor activation, despite the absence of such a pressor response in healthy subjects with intact sympathetic mechanisms. We investigated whether water drinking in normal subjects affected peripheral sympathetic neural discharge and its effect on vascular resistance. In nine normal human subjects, we examined the effect of water ingestion on muscle sympathetic neural activity from the peroneal nerve, as multi-unit bursts (muscle sympathetic nerve activity; MSNA) and as single-unit impulses (s-MSNA) with vasoconstrictor function, and on calf vascular resistance for 120 min. In each subject, water ingestion caused increases in s-MSNA and MSNA which peaked at 30 min after ingestion; they increased respectively (mean+/-S.E.M.) from 42+/-4 to 58+/-5 impulses/100 beats (P<0.01) and from 36+/-4 to 51+/-5 bursts/100 beats (P<0.001). There were corresponding increases in calf vascular resistance and in plasma noradrenaline levels. A significant correlation occurred between all of these data. In conclusion, measurement of MSNA has provided direct evidence that water drinking in normal human subjects increases sympathetic nerve traffic, leading to peripheral vasoconstriction. This sympathetic activation was not accompanied by significant changes in arterial blood pressure.

Individuals from multiplex insulin-dependent diabetes mellitus (IDDM) families express higher levels of TCRBV2S1 than controls.

T lymphocytes recognise peptide antigens through the T cell antigen receptor, which is composed of variable alpha and beta chains. There are forty-six functional variable regions on the beta chain. In this study the expression of the T cell receptor beta-chain variable regions 2S1 and 3S1, in a large cohort of multiplex insulin-dependent diabetes mellitus families, have been determined by use of monoclonal antibodies and flow cytometry. Peripheral blood was collected from these multiplex families and three control groups, healthy individuals, sporadic insulin-dependent diabetes mellitus patients and non-insulin-dependent diabetes mellitus patients. The level of TCRBV2S1 expression in the multiplex families was significantly higher than all the control groups for both the CD4+ and CD8+ T lymphocyte subsets. Detailed analysis of the family data showed that this increased expression was not associated with age, sex, HLA type or the diabetic phenotype. The TCRBV3S1 expression in all the diabetic cohorts was significantly lower than the healthy controls, in the CD4 subset only. Detailed analysis of the family data showed only the fathers TCRBV3S1 expression was lower than the healthy controls. This study gives further insight into TCRBV usage which could reflect the mechanism of the autoimmune response in IDDM multiplex families.

Male pseudohermaphroditism resulting from a novel mutation in the human steroid 5 alpha-reductase type 2 gene (SRD5A2).

The enzyme steroid 5 alpha-reductase, via NADPH, catalyses the conversion of testosterone to dihydrotestosterone, which is required for the embryonic differentiation of the external male genitalia and the prostate. An impairment of this reaction causes a form of male pseudohermaphroditism in which genetic males differentiate predominantly as phenotypic females. Molecular analysis of the 5 alpha-reductase type 2 gene in a patient with confirmed biochemical 5 alpha-reductase deficiency has resulted in the identification of a novel mutation, GAA to AAA, at codon 200. This mutation produces an amino acid change from glutamic acid to lysine, and may affect the ability of the enzyme to bind its co-factor.

Lack of acute effect of amylin (islet associated polypeptide) on insulin sensitivity during hyperinsulinaemic euglycaemic clamp in humans.

It is suggested that amylin (islet associated polypeptide), co-secreted with insulin from the pancreatic beta cells acts as a circulating hormone which opposes the action of insulin on muscle and increases hepatic glucose production. We have tested the effect of amylin in human subjects on postabsorptive glucose homeostasis and on insulin sensitivity using the euglycaemic hyperinsulinaemic clamp. The amylin used opposed insulin-mediated glucose disposal in rat soleus muscle at concentrations of 10 nmol/l. Seven subjects were studied on two occasions and infused with either amylin or placebo for 6 h, initially when postabsorptive and then during a euglycaemic hyperinsulinaemic clamp. Mean plasma amylin concentrations during the first 3 h were 2006 +/- 327 pmol/l during amylin infusion and 20 +/- 9 pmol/l during the control infusion. Amylin infusion had no effect on postabsorptive plasma concentrations of insulin (control: 32 +/- 16 vs amylin: 25 +/- 8 pmol/l) or glucose (5.1 +/- 0.1 vs 5.3 +/- 0.1 mmol/l). During the clamp, amylin concentrations were 1636 +/- 422 pmol/l when it was infused and 24 +/- 6 during control infusions. Plasma glucose and insulin concentrations were well matched during the control and amylin infusions (glucose: 4.7 +/- 0.1 vs 4.8 +/- 0.1 mmol/l; insulin: 198 +/- 37 vs 195 +/- 22 pmol/l). Exogenous glucose infusion rates were a mean of 13% lower than control values during the amylin infusion but were not statistically different (p = 0.17).(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of metastatic gastroenteropancreatic tumours by somatostatin receptor scintigraphy with [111In-DTPA-D-Phe1]-octreotide.

Most gastroenteropancreatic tumours express somatostatin receptors, allowing imaging using radiolabelled somatostatin analogues. Octreotide can be modified by coupling a DTPA moiety to the N-terminal D-phenylalanine to allow labelling with In111. We studied the comparative effectiveness of this radiopharmaceutical in identifying tumour extent. Twenty-two patients with metastatic gastroenteropancreatic tumours were scanned using [111In-DTPA-D-Phe1]-octreotide. In 11 patients with the carcinoid syndrome, one of six primary lesions was identified by CT scanning and by [111In-DTPA-D-Phe1]-octreotide scanning. Hepatic metastases were present in all patients, 9 of whom had positive scintigraphy. Two other sites of intra-abdominal uptake and four distant sites, not previously identified, were demonstrated. Five other distant sites were confirmed to be carcinoid metastases. All 11 patients with other gastroenteropancreatic tumours had positive scans, demonstrating 7/9 primary lesions, 12 intra-abdominal lesions, including hepatic metastases in all cases, and one distant lesion, all previously identified. Thus [111In-DTPA-D-Phe1]-octreotide imaging effectively identified the extent of metastatic disease from gastroenteropancreatic tumours, and confirmed lesions whose significance was uncertain following previous imaging procedures.

Naloxone-induced anorexia increases neuropeptide Y concentrations in the dorsomedial hypothalamus: evidence for neuropeptide Y-opioid interactions in the control of food intake.

We measured neuropeptide Y (NPY) concentration in microdissected hypothalamic nuclei, by radioimmunoassay, and NPY mRNA in the hypothalamus in rats treated systemically with the nonspecific opioid antagonist, naloxone, to produce mild anorexia. Twenty rats were treated with daily SC injections of naloxone (7.5 mg/kg); 20 were treated with vehicle alone. Naloxone produced a 7% reduction in food intake (p < 0.01) and a reduction in weight gain (p < 0.002). Neuropeptide Y concentrations were increased specifically in the dorsomedial nucleus of the hypothalamus (DMN) in rats treated with naloxone (6.8 +/- 0.7 fmol/micrograms protein vs. 3.1 +/- 1.0 fmol/micrograms protein, p < 0.05, n = 10 per group). Total hypothalamic NPY mRNA was unchanged. Neuropeptide Y-opioid interactions may be important in the control of food intake.

The effect of central blockade of kappa-opioid receptors on neuropeptide Y-induced feeding in the rat.

Neuropeptide Y (NPY) and the endogenous kappa-opioid receptor ligand, dynorphin (dyn), stimulate feeding when injected centrally in the rat. Norbinaltorphimine (norBNI, 25 nmol) reduced the feeding response to NPY (2.4 nmol) by 67% (P < 0.02). An additive effect of dynorphin and NPY was seen on food intake (saline 0.8 +/- 0.1, dyn 1.9 +/- 0.4, NPY 6.1 +/- 1.4, dyn and NPY 9.7 +/- 2.2). A component of NPY-induced feeding may be mediated by kappa-opioid neuronal systems.

Insulin and intestinal epithelial cell proliferation.

The effects of modification of the levels of endogenous plasma insulin on intestinal epithelial cell proliferation were investigated in rats maintained by total parenteral nutrition (TPN) using either a TPN diet that was high in glucose, or a low glucose (hypocaloric) TPN diet and in orally fed rats (normal and sham operated). The rats were put on their respective treatments for 7 days and were then injected with vincristine sulphate to arrest cells as they entered metaphase. Intestinal tissue was fixed for the determination of crypt cell production rate (CCPR) and blood plasma was taken for hormone radioimmunoassay. Sham operation had no effect on either plasma hormone levels or on CCPR. The standard TPN diet was associated with significantly reduced levels of gastrin, peptide YY and enteroglucagon. Gastrin and PYY were further reduced by the hypocaloric diet. However, plasma insulin was much increased in the TPN but not in the hypocaloric group. Small intestinal CCPR was reduced in the TPN groups, but no difference was observed between the standard and the low calorie TPN diets. The lack of difference in CCPR between the two TPN diets despite the massive elevation of plasma insulin strongly suggests that insulin does not have a substantial role in the control of gastrointestinal epithelial cell renewal.

A role for neuropeptide-Y, dynorphin, and noradrenaline in the central control of food intake after food deprivation.

A marked increase in food intake is observed in the rat after central injection of neuropeptide-Y (NPY), dynorphin, or noradrenaline (NA). Levels of both NPY and dynorphin are increased in the hypothalamus of food-deprived rats. The aim of this study was to explore the role of NPY, dynorphin, and NA in the central control of feeding after a period of food deprivation. We have investigated the effect of intracerebroventricular injection of a monoclonal antibody to NPY (NPYAb), a potent and selective kappa-opioid receptor antagonist norbinaltorphimine (norBNI), and the alpha-adrenergic antagonist phentolamine on fast-induced food intake. In animals provided with food after a 24-h fast, NPYAb given 10 min before presentation of food reduced food intake by 30% (P < 0.01) compared to that of animals pretreated with an antibody to chloroquine. A similar (34%; P < 0.05) reduction in fast-induced feeding occurred after pretreatment with norBNI. If norBNI was given together with NPYAb, then a reduction of 51% (P < 0.05) was observed. Pretreatment with phentolamine reduced fast-induced food intake by 39% (P < 0.05), with no evidence of an additive effect when phentolamine was given together with NPYAb. These data would support a role for endogenous NPY, dynorphin, and NA in the mediation of fast-induced feeding. NPY would seem to act independently of dynorphin, but through the same mechanism as NA.

Amino acid infusion blocks renal tubular uptake of an indium-labelled somatostatin analogue.

The Indium-labelled somatostatin analogue pentetreotide has been successfully developed for imaging of somatostatin receptor positive tumours. However there is significant renal tubular uptake of the radiolabelled peptide, which can obscure upper abdominal tumours and would preclude its use for targeted radiotherapy. The aim of this study was to determine whether amino acid infusion, which has been shown to block renal tubular peptide reabsorption, diminishes renal parenchymal uptake of this radiolabelled analogue. Eight patients being scanned with the 111In-labelled somatostatin analogue, pentetreotide, for localisation of gastroenteropancreatic tumours received an infusion of synthetic amino acids. The ratio of isotope uptake in kidney to that in spleen was assessed, and compared to the ratio for matched control patients, to determine if amino acid infusion reduced renal parenchymal uptake of the radiopharmaceutical. The amount of isotope in the urine was determined to ensure that any effect of the amino acid infusion was unrelated to changes in clearance. Infusion of amino acids significantly reduced renal parenchymal uptake of isotope at 4 h. There was a non-significant increase in urinary clearance of isotope over the 4 h, consistent with reduced reuptake and a lack of effect on glomerular filtration rate. This technique, by preventing renal damage, may allow the use of this somatostatin analogue for local radiotherapy, and could be of wider value in blocking tubular re-uptake of potentially nephrotoxic agents, such as radiolabelled Fab fragments.

Increased neuropeptide-Y messenger ribonucleic acid (mRNA) and decreased neurotensin mRNA in the hypothalamus of the obese (ob/ob) mouse.

The obese hyperglycaemic ob/ob mouse exhibits hyperphagia and other abnormalities of hypothalamic function. We measured hypothalamic concentrations of four peptides implicated in the control of appetite and energy expenditure, neuropeptide-Y (NPY), neurotensin, galanin, and somatostatin, by RIA and their respective mRNAs using semiquantitative Northern blotting. Using lean (+/+) mice as controls, we found unchanged concentrations of NPY, galanin, and somatostatin and a 25% reduction in neurotensin (P < 0.01). Neurotensin mRNA was similarly decreased (by 30%; P < 0.02), while NPY mRNA was increased 3-fold (P < 0.01). Centrally administered neurotensin decreases food intake, whereas NPY potently stimulates food intake. An increase in NPY gene expression together with reductions in neurotensin concentration and mRNA in the hypothalamus may be implicated in the development of hyperphagia and other neuroendocrine abnormalities seen in the ob/ob mouse.