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Biomedical subjects

Keith J Lindley

Publications and source records attributed to Keith J Lindley.

12 recordsLinked to original sources

Chronic pancreatitis.

Chronic pancreatitis (CP) is characterised by pancreatic inflammation and fibrosis leading eventually to destruction of pancreatic parenchyma and loss of exocrine and endocrine function. A model of interactions between environmental triggers of pancreatic inflammation and disease susceptibility or modifying genes (including PRSS1, SPINK1 and CFTR) provides a framework within which to understand disease pathogenesis. Early in the disease, when fibrosis is mild and pancreatic damage limited, it is difficult to distinguish CP from recurrent acute pancreatitis (RAP) although it is likely these represent opposite ends of a spectrum of disease with a common aetiology in which CP represents either a later disease stage or disease in individuals predisposed to generate a chronic fibrogenic inflammatory response. Pain is a dominant feature resulting in part from neuroimmune interactions within the pancreas. Diagnosis at an early stage of disease is challenging, though in later stages is dependent upon the demonstration of pancreatic fibrosis and duct ectasia using one or more imaging modalities including transabdominal and endoscopic ultrasound, CT and MRCP or ERCP. Current treatments are largely supportive and reactive. The challenge for pediatricians is to achieve diagnosis at an early stage of the disease and to develop treatments that can alter its natural history.

Child↗

Long-term outcome of intractable ulcerating enterocolitis of infancy.

BACKGROUND: Chronic enterocolitis is rare in infancy and accounts for less than 0.5% of all newly diagnosed inflammatory bowel disease (IBD) in the UK. Presentation at this young age is usually indicative of underlying immunodeficiency/immunodysregulation. A group of such infants suffer intractable ulcerating enterocolitis of infancy (IE) in which there is a pan-enteritis with marked oro-anal involvement and deep flask like mucosal ulcers throughout the colon. METHODS: Retrospective review of presenting features, treatment and long-term outcome in a series of 8 children with typical IE. RESULTS: The 8 children were aged between 1 and 4 weeks at onset (median 2 weeks, mean 2.3 weeks), of which 7 were followed up for 2-22 years (median 7.5 years, mean 11 years). All 8 children had an intractable disease course requiring a colectomy for control of symptoms. The median age at colectomy was 1.7 years (range 4 months-4 years). Three children developed a generalised lymphadenopathy due to uncontrolled EBV-related lymphoid proliferations (ages 4, 12, 18). These comprised a monomorphous B-lymphoycte lympho-proliferative disorder, a large pleomorphic follicular lymphoma, and a high grade pleomorphic B cell non-Hodgkin's lymphoma. CONCLUSIONS: Infants with IE have a high risk of developing lymphomatous proliferations that appears to be related to the underlying immunodysregulation. Use of aggressive immunosuppression and acquisition of EBV infection appears to accelerate this process; hence we advocate early colectomy in confirmed cases. In children with IE screening for EBV and vigilance for abnormal lymphoid proliferations is paramount.

Adolescent↗

Contemporary strategies in the diagnosis and management of neonatal hyperinsulinaemic hypoglycaemia.

Congenital hyperinsulinism (CHI) is a genetically and phenotypically diverse syndrome. Key management issues involve early diagnosis by ensuring that appropriate samples are taken at the point of hypoglycaemia, prevention of recurrent hypoglycaemia, and detailed characterisation of the clinical, biochemical, and genetic features of each case. Infants with persistent diazoxide resistant CHI require evaluation at specialist referral centres equipped to differentiate those with focal (fo-HI) and diffuse (di-HI) pancreatic disease. Fo-HI is treated with selective pancreatic resection but di-HI is treated by surgery only if intensive medical management regimes are not efficacious.

Blood Chemical Analysis↗

Genetics and pathophysiology of hyperinsulinism in infancy.

Hyperinsulinism in infancy (HI) is a condition of neonates and early childhood. For many years the pathophysiology of this potentially lethal disorder was unknown. Advances in the genetics, histopathology and molecular physiology of this disease have now provided insights into the causes of beta-cell dysfunction and revealed levels of diversity far in excess of our previous knowledge. These include defects in ion channel subunit genes and mutations in several enzymes associated with beta-cell metabolism and anaplerosis. In most cases, beta-cell pathophysiology leads to an alteration in the function of ATP-sensitive K(+) channels. This can manifest as 'channelopathies' of K(ATP) channels through gene defects in ABCC8 and KCNJ11 (Ch.11p15); or as a result of 'metabolopathies' through defects in the genes encoding glucokinase (GCK, Ch.7p15-p13), glutamate dehydrogenase (GLUD1, Ch.10q23.3) and short-chain L-3-hydroxyacyl-CoA dehydrogenase (HADHSC, Ch.4q22-q26). This review focuses upon the relationship between the causes of HI and therapeutic options.

Adenosine Triphosphate↗

Programming of defective rat pancreatic beta-cell function in offspring from mothers fed a low-protein diet during gestation and the suckling periods.

Poor fetal and infant nutrition has been linked to impaired glucose tolerance in later life. We studied the effect of protein deficiency during gestation and the suckling period in a rat model and found that poor nutrition 'programmes' pancreatic beta-cell GK (glucokinase; known as the glucose sensor) and glucose-stimulated insulin secretion response in newborn, suckling and adult rat offspring. Pregnant female rats were divided into three groups: a control group was kept on a normal protein (20%) diet, another group was fed a low-protein (LP) (6%) diet during gestation and suckling periods (LP-G + S group) and another was fed a LP diet during gestation then a normal protein diet during the suckling period (LP-G group). The pulsatile glucose-stimulated insulin secretion response was acutely disrupted and the peak insulin secretion was markedly decreased in newborn and 3-week-old offspring of the LP-G + S group compared with the control group. Also, there was an altered pulsatile secretory response in adults of the LP-G + S and 3-week-old and adult offspring of the LP-G groups compared with the control group. GK protein levels, detected by Western blotting, were decreased in newborn and 3-week-old offspring of both LP-G + S and LP-G groups compared with the control groups. The Km and Vmax of GK were altered. The prenatal and postnatal LP diet appeared to have a permanent effect in increasing the affinity of GK for glucose (indicated by decreased Km values) and decreasing the Vmax. This showed that the critical period of programming of the function of GK was after birth and during the postnatal weaning period, since the adult offspring of the LP-G + S group when fed a normal protein diet showed no reversal in the Km values of the enzyme. Similar experiments in adult offspring of the LP-G group showed normalization of the Km values of GK at 3 weeks of age. In conclusion, fetal and infantile nutrition 'programmes' pancreatic beta-cell function; poor nutrition during this period caused irreversible effects on glucose homoeostatic mechanisms in the offspring, which may predispose the offspring to diabetes in later life.

Aging↗

Hyperinsulinism in infancy: from basic science to clinical disease.

Ion channelopathies have now been described in many well-characterized cell types including neurons, myocytes, epithelial cells, and endocrine cells. However, in only a few cases has the relationship between altered ion channel function, cell biology, and clinical disease been defined. Hyperinsulinism in infancy (HI) is a rare, potentially lethal condition of the newborn and early childhood. The causes of HI are varied and numerous, but in almost all cases they share a common target protein, the ATP-sensitive K+ channel. From gene defects in ion channel subunits to defects in beta-cell metabolism and anaplerosis, this review describes the relationship between pathogenesis and clinical medicine. Until recently, HI was generally considered an orphan disease, but as parallel defects in ion channels, enzymes, and metabolic pathways also give rise to diabetes and impaired insulin release, the HI paradigm has wider implications for more common disorders of the endocrine pancreas and the molecular physiology of ion transport.

Animals↗

Infantile hyperinsulinism associated with enteropathy, deafness and renal tubulopathy: clinical manifestations of a syndrome caused by a contiguous gene deletion located on chromosome 11p.

We describe the clinical features of a new syndrome causing hyperinsulinism in infancy (HI), severe enteropathy, profound sensorineural deafness, and renal tubulopathy in three children born to two pairs of consanguineous parents. This combination of clinical features is explained by a 122-kb contiguous gene deletion on the short arm of chromosome 11. It deletes 22 of the 39 exons of the gene coding for the SUR1 component of the KATP channel on the pancreatic beta-cell thereby causing severe HI. It also deletes all but two of the 28 exons of the USH1C gene, which causes Usher syndrome and is important for the normal development and function of the ear and the eye, the gastrointestinal tract, and the kidney, thereby accounting for the symptoms of deafness, vestibular dysfunction and retinal dystrophy seen in type 1 Usher syndrome, diarrhoea, malabsorption, and tubulopathy. This contiguous gene deletion provides important insights into the normal development of several body organ systems.

Child, Preschool↗

Surgery of persistent hyperinsulinaemic hypoglycaemia.

Hyperinsulinism (HI) is the commonest cause of persistent or recurrent hypoglycaemia in childhood. HI is genetically and phenotypically diverse. Key management issues involve early diagnosis by insuring that appropriate investigations are undertaken at the point of hypoglycaemia, prevention of recurrent hypoglycaemia and clinical, biochemical and genetic characterisation of the HI syndrome. Children with persistent diazoxide resistant HI require investigation at specialist centres to differentiate those with a generalised disorder of the pancreas (diffuse HI; di-HI) from those with localised abnormalities within the pancreas (focal HI; fo-HI). Fo-HI may be managed by selective pancreatic resection of the focal abnormality. Di-HI is only managed by surgery if combination drug therapies are unable to prevent hypoglycaemia. Pancreatic beta-cell dysfunction persists following subtotal pancreatectomy of di-HI.

Decision Trees↗

The nature of colitis in chronic granulomatous disease.

BACKGROUND: Patients with chronic granulomatous disease (CGD) may have gastrointestinal manifestations, commonly colitis. The etiology, prevalence, and inflammatory process of CGD colitis are unclear. OBJECTIVES: To characterize the inflammatory process of CGD colitis and to compare it with other inflammatory bowel disorders. METHODS: Colonic mucosal biopsies from 8 CGD patients were immunostained for eosinophils, neutrophils, macrophages, and adhesion molecules (ICAM; VCAM, E-selectin) and compared with normal and diseased controls (allergic colitis, ulcerative colitis, and melanosis coli). Cell types were counted and expressed as cell/mm2. RESULTS: The inflammatory infiltrate in CGD colitis differed from the normal controls by an increase in eosinophils (110; 48-176 [median and range] versus 14.5; 3-30; P < 0.005) and macrophages (291.5; 203-480 versus 38.5; 27-64; P < 0.005). There was a paucity of neutrophils compared to ulcerative colitis (10; 0-101 versus 315.5; 78-688; P < 0.005). Expression of HLA-DR was increased in the epithelium and vascular endothelium in CGD compared with normal controls. Patterns of expression of the adhesion molecules differed significantly in CGD from those in other inflammatory bowel diseases: intracellular adhesion molecule-1 was more strongly expressed in the lamina propria, vascular adhesion molecule-1 was more patchily expressed, and E-selectin was present only in the small vessels. CONCLUSIONS: The mechanism of inflammation and profile of inflammatory mediators in CGD colitis differs from that in other inflammatory bowel diseases.

Biopsy↗

Small-intestinal dysfunction accompanies the complex endocrinopathy of human proprotein convertase 1 deficiency.

We have previously described the only reported case of human proprotein convertase 1 (PC1) deficiency, in a female (Subject A) with obesity, hypogonadism, hypoadrenalism, and reactive hypoglycemia. We now report the second case of human PC1 deficiency (Subject B), also due to compound heterozygosity for novel missense and nonsense mutations. While both subjects shared the phenotypes of obesity, hypoadrenalism, reactive hypoglycemia, and elevated circulating levels of certain prohormones, the clinical presentation of Subject B was dominated by severe refractory neonatal diarrhea, malabsorptive in type. Subsequent investigation of Subject A revealed marked small-intestinal absorptive dysfunction, which was not previously clinically suspected. We postulate that PC1, presumably in the enteroendocrine cells, is essential for the normal absorptive function of the human small intestine. The differences in the nature and severity of presentation between the two cases cannot readily be explained on the basis of allelic heterogeneity, as the nonsense and missense mutations from both subjects had comparably severe effects on the catalytic activity of PC1. Despite Subject A's negligible PC1 activity, some mature ACTH and glucagon-like peptide 17-36(amide) were detectable in her plasma, suggesting that the production of these hormones, at least in humans, does not have an absolute dependence on PC1. The presence of severe obesity and the absence of growth retardation in both subjects contrast markedly with the phenotype of mice lacking PC1 and suggest that the precise physiological repertoire of this enzyme may vary between mammalian species.

Animals↗

BPDZ 154 activates adenosine 5'-triphosphate-sensitive potassium channels: in vitro studies using rodent insulin-secreting cells and islets isolated from patients with hyperinsulinism.

A novel ATP-sensitive potassium channel (K(ATP)) channel agonist, BPDZ 154 (6,7-dichloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide), was synthesized, and its effects on insulin-secreting cells were evaluated using electrophysiology, (86)Rb(+) and (45)Ca(2+) efflux, and RIA determinations of insulin secretion. BPDZ 154, an analog of diazoxide, inhibited both glucose-induced insulin secretion from isolated perifused islets and the secretion of insulin induced by glucose and tolbutamide. These effects were mediated by the activation of ATP-sensitive potassium channels because BPDZ 154 induced a concentration-dependent increase in channel activity that was inhibited by the sulfonylurea tolbutamide and the imidazoline efaroxan. In beta-cells isolated from patients with either nontypical hyperinsulinism (preserved K(ATP) channel function) or from the control areas of the pancreas of patients with focal hyperinsulinism, BPDZ 154 activated K(ATP) channels and was found to be more effective and less readily reversible than diazoxide. By contrast, it was not possible to activate K(ATP) channels by either diazoxide or BPDZ 154 in beta-cells from patients with hyperinsulinism as a consequence of defects in K(ATP) channel function. In beta-cells isolated from a patient with pancreatic insulinoma, K(ATP) channels were readily recorded and modulated by BPDZ 154. These data suggest that BPDZ 154 or BPDZ 154-like compounds may have therapeutic potential in the treatment of certain forms of hyperinsulinism.

Adenosine Triphosphate↗