The hPLIC proteins may provide a link between the ubiquitination machinery and the proteasome

Although there is a binding site on the proteasome for the polyubiquitin chains attached to degradation substrates by the ubiquitination machinery, it is currently unclear whether in vivo the activities of the ubiquitination machinery and the proteasome are coupled. Here we show that two human homologs of the yeast ubiquitin-like Dsk2 protein, hPLIC-1 and hPLIC-2, physically associate with both proteasomes and ubiquitin ligases in large complexes. Overexpression of hPLIC proteins interferes with the in vivo degradation of two unrelated ubiquitin-dependent proteasome substrates, p53 and IkappaBalpha, but not a ubiquitin-independent substrate. Our findings raise the possibility that the hPLIC proteins, and possibly related ubiquitin-like family members, may functionally link the ubiquitination machinery to the proteasome to affect in vivo protein degradation.

Recurrent alcoholic ketoacidosis with hyperglycaemia in a non-diabetic patient

A39-year-old man was admitted urgently with abdominal pain and vomiting to a surgical ward. He had a history of excessive alcohol intake and previous attacks of acute alcoholrelated pancreatitis. Examination was unremarkable apart from a tachycardia of 120/minute in sinus rhythm and generalized abdominal tenderness. Investigations revealed normal haemoglobin, urea and electrolyte levels. White cell count (WCC) was 11.5/mm3 and plasma glucose 13.1 mmol/litre (there was no past or family history of diabetes). Urine was heavily positive for ketones. Serum amylase was normal. Arterial blood gases showed a metabolic acidosis (pH 7.18, pCO2 2.1 kPa, pO2 18.7 kPa, base deficit 19 mmol/litre and standard bicarbonates 10 mmol/litre). No definite diagnosis was made, but the patient was treated with intravenous 0.9% sodium chloride (NaCl) infusion, and his symptoms settled and the blood gases normalized spontaneously over the next 1–2 days. Apart from the initial raised plasma glucose, all subsequent levels were normal.

Three months later the patient was again admitted urgently with abdominal pain and vomiting, this time to a medical ward. In the period since his last admission he had continued to drink excessive amounts of alcohol, and had had a particularly heavy ‘binge’ over the preceding 2–3 days. On examination he was moderately dehydrated and tachycardic, with hyperventilation and generalized abdominal tenderness. Serum amylase and electrolytes were normal, but urea and creatinine were slightly raised at 8.1 mmol/litre and 142 μmol/litre respectively. WCC was 22.1/mm3 and urine was heavily positive for ketones. Plasma glucose was 13.9 mmol/litre. Arterial blood gases again showed a metabolic acidosis (pH 7.22, pCO2 1.5 kPa, pO2 18.5 kPa, base deficit 20 mmol/litre and standard bicarbonate 8 mmol/litre). A serum lactate level was taken at the time and later returned at 3.9 mmol/litre. A diagnosis of either euglycaemic diabetic ketoacidosis or alcoholic ketoacidosis was made. He was treated with 0.9% NaCl intravenous rehydration, as well as a glucose–potassium–insulin infusion. He improved clinically and biochemically over the next 2 days, and again, apart from the initial raised plasma glucose level, all subsequent levels were normal.

Six weeks after the second admission an outpatient glucose tolerance test was performed, with the patient on a free diet and no medication. The fasting plasma glucose level was 7.3 mmol/litre, and the plasma glucose level 2 hours after a loading dose of 75 g of glucose was 6.4 mmol/litre. Over the subsequent 2 years the patient had 3 further hospitalizations (one with a haematemesis as a result of a Mallory–Weiss oesophageal tear, and two with non-specific abdominal pain). No further episodes of alcoholic ketoacidosis occurred, nor did the patient develop diabetes.

The secreted glycoprotein CREG enhances differentiation of NTERA-2 human embryonal carcinoma cells

Differentiation of the human embryonal carcinoma cell line NTERA-2 is characterized by changes in morphology, altered patterns of gene expression, reduced proliferative potential, and a loss of tumorigenicity. The cellular repressor of E1A-stimulated genes, CREG, was previously shown to antagonize transcriptional activation and cellular transformation by the Adenovirus E1A oncoprotein. These properties suggested that CREG may function to inhibit cell growth and/or promote differentiation. Here we show that CREG is a secreted glycoprotein which enhances differentiation of NTERA-2 cells. Northern blot analysis reveals that, although CREG mRNA is widely expressed in adult tissues, CREG mRNA is not significantly expressed in pluripotent mouse embryonic stem cells or NTERA-2 embryonal carcinoma cells. CREG mRNA is rapidly induced upon in vitro differentiation of both mouse embryonic stem cells and human NTERA-2 cells. We show that constitutive expression of CREG in NTERA-2 cells enhances neuronal differentiation upon treatment with retinoic acid. Media enriched in CREG was also found to promote NTERA-2 differentiation in the absence of an inducer such as retinoic acid. These studies suggest that secreted CREG protein participates in a signaling cascade important for differentiation of pluripotent stem cells such as those found in teratocarcinomas.

Intraarterial catheter-directed thrombolysis: urokinase versus tissue plasminogen activator

The purpose of this study was to evaluate the differences between tissue plasminogen activator (TPA) and urokinase (UK) in the management of ischemic limbs. A total of 58 limbs (24 in the TPA group and 34 in the UK group) in 53 patients were studied prospectively. The two groups were based on the surgeon's preference for lytic agent. The dose regimen for UK was 150,000 IU/hr over 1/2 to 2 hr followed by a continuous infusion of 50,000 IU/hr. TPA was given as a 5-mg bolus followed by 1 mg/hr. Both groups received heparin at a rate of 400 IU/hr through the side arm of the arterial sheath. There was no significant difference in efficacy between UK and TPA, but TPA acted faster and had a higher incidence of bleeding complications.

Characteristics of insulin requiring diabetes in rural northern Ethiopia--a possible link with malnutrition?

We have examined 100 consecutive insulin-treated diabetic patients from the Diabetic Clinic at Mekelle Hospital in Tigray, Northern Ethiopia; an area of low socio-economic status recently affected by severe famine. The study was conducted over a six month period (1997). Mean age of onset of diabetes was 27 +/- 10 y (SD) and there was a male excess (3.1:1.0). Body Mass index (BMI) at diagnosis was very low at 15.8 +/- 2.8. Because of erratic insulin supply 48 (48%) had interrupted insulin treatment in the past for a mean duration of 9 +/- 12 weeks (range 1-78). Despite this, only 2 (4%) developed ketoacidosis (DKA). The patients thus have features suggestive of malnutrition-related diabetes mellitus (MRDM) possibly of the "malnutrition-modulated" (MMDM) type in view of the apparent absence of overt exocrine pancreatic disease. The famine in this area 10 years previously may be of relevance to the aetiology of diabetes in these patients.

Brittle diabetes characterised by recurrent hypoglycaemia

There is little information on the clinical characteristics of "brittle" Type 1 (insulin-dependent) diabetic patients with predominantly hypoglycaemic instability. From a total cohort of 381 brittle diabetic patients from various parts of the United Kingdom, 64 (17%) had life-disrupting instability due to recurrent hospital admissions with hypoglycaemia. Compared to brittle patients with recurrent ketoacidosis (DKA), who comprised 59% of the total, those with recurrent hypoglycaemia were characterised by older mean age (34 +/- 20 v 22 +/- 11 y, p < 0.001), and more equal sex distribution (53% v 71% female, p < 0.05). Patients with "mixed brittleness" (24% of total) were intermediate between the other groups, in terms of both age and female predominance. Physicians in charge of patients with hypoglycaemic brittle diabetes considered psychosocial factors to be frequent underlying causes, though organic conditions such as lost hypoglycaemic warnings and alcohol abuse were also mentioned. Factitious insulin overdose was diagnosed in 3 patients. We conclude that hypoglycaemic brittle diabetes is a small but important sub-group of the overall brittle syndrome. It differs in age and sex distribution from the more common syndrome of recurrent DKA.

Evaluating your practice

In this series you have learnt about research as it applies to researchers in general practice. You have seen how a research question is defined, examined how to search the medical literature to discover what is known about the topic, seen the use of qualitative and quantitative approaches to data collection and had explained to you some of the problems of data collection and analysis. As an active GP you may have found the topics interesting, but who has time for research? This final article in the series is titled 'Evaluating your own practice'. Every day you carry out this activity. Simple items like how long do your patients wait, or is there enough money earned to cover expenses? These are things you have been evaluating for a long time. You are an expert at evaluating many aspects of your practice. What I want to try and do in this brief article is to show you how knowledge of research approaches can help you by making it easier to carry out an evaluation and arrive at more accurate conclusions.

Hyponatraemia: biochemical and clinical perspectives

Hyponatraemia is a common bio-chemical abnormality, occurring in about 15% of hospital inpatients. It is often associated with severe illness and relatively poor outcome. Pathophysiologically, hyponatraemia may be spurious, dilutional, depletional or redistributional. Particularly difficult causes and concepts of hyponatraemia are the syndrome of inappropriate antidiuresis and the sick cell syndrome, which are discussed here in detail. Therapy should always be targeted at the underlying disease process. 'Hyponatraemic symptoms' are of doubtful importance, and may be more related to water overload and/or the causative disease, than to hyponatraemia per se. Artificial elevation of plasma sodium by saline infusion carries the risk of induction of osmotic demyelination (central pontine myelinolysis).

A cellular repressor of E1A-stimulated genes that inhibits activation by E2F

The adenovirus E1A protein both activates and represses gene expression to promote cellular proliferation and inhibit differentiation. Here we report the identification and characterization of a cellular protein that antagonizes transcriptional activation and cellular transformation by E1A. This protein, termed CREG for cellular repressor of E1A-stimulated genes, shares limited sequence similarity with E1A and binds both the general transcription factor TBP and the tumor suppressor pRb in vitro. In transfection assays, CREG represses transcription and antagonizes 12SE1A-mediated activation of both the adenovirus E2 and cellular hsp70 promoters. CREG also antagonizes E1A-mediated transformation, as expression of CREG reduces the efficiency with which E1A and the oncogene ras cooperate to transform primary cells. Binding sites for E2F, a key transcriptional regulator of cell cycle progression, were found to be required for repression of the adenovirus E2 promoter by CREG, and CREG was shown to inhibit activation by E2F. Since both the adenovirus E1A protein and transcriptional activation by E2F function to promote cellular proliferation, the results presented here suggest that CREG activity may contribute to the transcriptional control of cell growth and differentiation.

Impact of age and cranial irradiation on radiographic skeletal pathology in children with acute lymphoblastic leukemia

BACKGROUND

Symptomatic osteopenia is a common form of morbidity in children with acute lymphoblastic leukemia (ALL) before, during, and after treatment. A causal role for corticosteroids has been proposed, but other investigators have suggested that cranial irradiation is an important factor contributing to this disorder.

PROCEDURE

In this study of children with ALL, all of whom received steroids, skeletal morbidity was assessed radiographically by an observer who was blinded to the ages of the children, their risk categorization (and related treatment), and the timing of the assessments with respect to the administration of therapy.

DISCUSSION

Skeletal morbidity was most prevalent in older subjects who had been given cranial radiotherapy. However, there was no difference in the frequency of fractures in two groups of younger children (< or = 9 years of age), one irradiated and the other not.

CONCLUSIONS

It is likely that corticosteroid therapy plays an important part in the pathogenesis of this disorder. The role played by cranial irradiation is much less certain.

Noncommunicable disease management in resource-poor settings: a primary care model from rural South Africa

Noncommunicable diseases (NCDs) such as hypertension, asthma, diabetes and epilepsy are placing an increasing burden on clinical services in developing countries and innovative strategies are therefore needed to optimize existing services. This article describes the design and implementation of a nurse-led NCD service based on clinical protocols in a resource-poor area of South Africa. Diagnostic and treatment protocols were designed and introduced at all primary care clinics in the district, using only essential drugs and appropriate technology; the convenience of management for the patient was highlighted. The protocols enabled the nurses to control the clinical condition of 68% of patients with hypertension, 82% of those with non-insulin-dependent diabetes, and 84% of those with asthma. The management of NCDs of 79% of patients who came from areas served by village or mobile clinics was transferred from the district hospital to such clinics. Patient-reported adherence to treatment increased from 79% to 87% (P = 0.03) over the 2 years that the service was operating. The use of simple protocols and treatment strategies that were responsive to the local situation enabled the majority of patients to receive convenient and appropriate management of their NCD at their local primary care facility.

The effects of carcinogenic methylcholanthrene on carbohydrate residues of NK cells

The present study examines the effect of methylcholanthrene (MCA), a a carcinogenic polycyclic hydrocarbon, on the carbohydrate receptor determinants (RD) on natural killer (NK) cell surface using the bead-coupled lectin assay. Murine NK cells exhibited different degrees of preferential binding to the specific lectins tested. Of the ten lectins tested, five exhibited a positive binding affinity while the remaining five exhibited no or insignificant binding. NK cells bind to beads derivatized with mannose specific lectins: Concanavalin A (Con A), Lens culinaris, and Pisum sativum. NK cells also bind to other lectin beads such as Triticum vulgaris (GalNac) and Vicia villosa (D-GlcNAc). All these lectin beads exhibited greater than 90% adhesion. The underivatized control beads exhibited no NK binding. The NK cells that were exposed to MCA for 2 h demonstrated a significant decrease in lectin bead-cell coupling in a dose dependent manner. MCA (10 micrograms/mL) caused a 17.8%, 40% and 4.7% decrease in binding affinity when introduced to the mannose specific lectins; Con A, L. culinaris and P. sativum beads, respectively. The binding of T. vulgaris and V. villosa to NK cells was inhibited (23.4% and 28%) by MCA treatment. An increase in the dose to 20 micrograms/mL resulted in a greater inhibition in binding affinity towards lectin beads. Con A, 35.3%, L. culinaris, 62.6%, P. sativum, 30.9%, T. vulgaris, 44.2% and V. villosa, 46.2%. The effect of MCA activation and cytotoxic response. Hydrolysis of PI metabolites (PIP and PIP2) cause generation of secondary messenger: inositol-1,4,5-triphosphate and diacylglycerol, both of which elicit an immune response through their products (Ca2+ and PKC) respectively. Identification of the relationship between receptor level, induction of second messenger and cytotoxic activity may resolve the molecular basis of suppression of NK cytotoxicity by MCA and other PAH compounds.