A molecular form of memory protects the brain from the effects of acute hypoxia [abstract]

Long-term potentiation (LTP) is a molecular engram of memory. Previous work has demonstrated that LTP decreases the sensitivity of glutamate receptors in the rat hippocampus. Glutamate has beem implicated in the pathogenesis of hypoxic/ischaemic damage. We therefore tested the hypothesis that LTP could reduce the effects of LTP on hypoxia in the rat hippocampus. The effects of LTP on hypoxia were measured by the changes in the extracellular potentials recorded from the hippocampal slice. Hypoxia was induced by perfusing the slice with artificial cerebrospinal fluid that contained varying concentrations of oxygen. Each slice was initially exposed to the hypoxic medium for 1.5-3.0 minutes. This led to a decrease in the potentials, which recovered to control levels within 5 minutes. Repeat exposure to the same hypoxic medium for the same duration as the first, also caused a reduction in the potentials. There was no significant difference between the degree of reduction caused by the first or second exposure for all types of hypoxic media tested (p >0.05; paired t test). In some slices, LTP was induced after the first hypoxic exposure. LTP brought about an inhibition of the reduction in potentials caused by the second hypoxic insult; the differences in reducation in potentials were highly significant for all the hypoxic media used (p <0.01; paired t test). The neuroprotective effects of LTP were not prevented by cyclothiazide (an inhibitor of AMPA receptor desensitization) or NOS inhibitors (antagonists of intracellular nitric oxide production). These compounds have been shown to be effective in blocking the effects of LTP on the actions of exogenously applied AMPA and NMDA, respectively. The neuroprotective effects of LTP were similar to that of propentofylline, a known neuroprotective compound. We conclude that LTP causes an appreciable protection of the hippocampus slices to in-vitro models of acute hypoxia. There have been reports that there is a possible inverse relationship between educational attainment and the development of dementia and the results of our study may have a role to play in this relationship. (AU)

Autism in Jamaica

This paper reviews childhood autism, a serious psychopathological disorder, with emphasis placed on aetiology and management; and outlines briefly the care of the autistic population in a few well organized programmes existing in Jamaica. There is a need for increased awareness, local research and dissemination of information to appropriate personnel and organizations.(Au)

Hypoxic ischaemic encephalopathy at the Mount Hope Women's Hospital, Trinidad - abstract

Hypoxic Ischaemic Encephalopathy (HIE) is a clinical syndrome which develops following foetal distress and a poor response by the infant to the birth process. Severe HIE can lead to death and severe neurological abnormalities. The aim of this study was to determine the incidence and outcome of babies who developed HIE over two 3-year periods, 1982-1984 and 1990-1992, at the Mt. Hope Women's Hospital (MHWH), Trinidad. The records of all inborn babies admitted to the Neonatal Unit, MHWH, with a diagnosis of HIE were studied. Those with proven meningitis, hypocalcaemia, irritability and hypoglycaemia were also excluded. Information collected included maternal characteristics, labour, birth and infant development up to 1 year. The overall incidence for the two study periods was 3.85 per 1000 live births (1982-1984) and 5.19 per 1000 live births (1990- 1992), which was not statistically significant. There was no statistical difference with regard to maternal age, parity, gestation, ethnicity, marital status, antenatal problems, foetal distress, infant gender and Apgar scores at 1 and 5 minutes. Significantly more mothers had antenatal care and more babies developed normally during the second study period. Significantly more mothers had Stage 1 of labour lasting longer than 15 hours in the first study period. There was no difference in the proportion of babies who died during the two study periods and a significantly higher proportion of babies were normal up to one year in the second study period. Like the perinatal mortality rate, HIE did not change with time at the Mt. Hope Women's Hospital (AU)

Continuous ambulatory peritoneal dialysis (CAPD) in patients with diabetes mellitus and chronic renal failure. Use of erythropoietin for treatment of anaemia of chronic renal failure - abstract

The renal replacement options in ERSD are (1) Haemodialysis (HD) in hospital or at home; (2) Peritoneal Dialysis: intermittent (IPD), continuous ambulatory (CAPD), continuous cyclic (machine) (CCPD); (3) Renal transplantation: living donor kidney and cadaver donor kidney and (4) Haemofiltration. Since 1979, there has been a phenomenal growth in the number of patients on chronic peritoneal dialysis, increasing from 2,000 patients worldwide to over 75,000 in 1992. This accounts for 14 per cent of patients on dialysis worldwide. The percentage of patients on CAPD is 6 percent in Japan, 51 percent in the United Kingdom and 93 percent in Mexico. CAPD is the cheapest form of dialysis in Europe and Canada and as cheap as home haemodialysis in the USA. In the USA, 1 in 3 new patients commenced on CAPD is diabetic. Data from the United States Renal Data System (USRDS) show that for primary renal disease in the non-diabetic, survival on CAPD is as good as haemodialysis. In the diabetics younger than 50 years, survival on CAPD is better than HD, but, over 50 years, there is no difference in survival. This applies for both Blacks and Whites. There are advantages for CAPD for diabetic patients when compared to HD. There is rapid establishment as with home therapy, training usually taking about three weeks; a partner is not essential; there are fewer hypotensive episodes and there is minimal stress on the cardiovascular system. One of the main disadvantages is peritonitis. Other less common problems are obstruction of the peritoneal catheter, tunnel infections and peritoneal thickening, leading to loss of peritoneal membrane surface. The main symptoms and signs of peritonitis are cloudly dialysate fluid, fever, abdominal pain and tenderness. Major improvements in the type of catheter, the type of giving sets and aseptic techniques have led to reduced incidence of peritonitis and patient mortality. The use of Erythropoietin in Patients with Chronic Renal Failure - Erythropoietin is normally produced in the peritubular interstitial cells of the kidneys. About 10 percent is produced in the liver, and there are no pre-formed stores of erythropoietin. Hypoxia increases de novo production of erythropoietin. It recruits and maintains the survival of the erythroid progenitor cells and promotes their maturation. The main condition in which erythropoietin is deficient is chronic renal failure, but it has also been found deficient in patients with cancer, chronic inflammations and chronic infections. Erythropoietin has been produced by genetic engineering, and its major indication is for the treatment of anaemia of chronic renal failure patients on haemodialysis, CAPD and also for predialysis patients (AU)

Analysis of 81 cases of acute chest syndrome in adult patients with sickle-cell disease in Curacao - abstract

All patients more than 14 years old with sickle-cell disease (SCD) discharged from hospital with a diagnosis of acute chest syndrome (ACS) from January, 1980 to December, 1981 were enrolled in this retrospective study. Data were collected from patients' records to investigate frequency, risk factors, effect of intravenous heparin and outcome in ACS. There were 109 adult SCD patients of whom 53 (49 per cent) were admitted for 81 episodes of ACS. Hb SS and Hb SC patients were affected equally often. Chest pain was the most frequent presenting symptom (64 per cent) and 91 per cent of patients had pulmonary abnormalities on physical examination, but only 45 per cent had radiological evidence of ACS at diagnosis. Forty-three per cent of sputum cultures grew pathogenic micro-organisms. The overall case-fatality rate was 6 per cent. All 5 non-survivors were female Hb SS patients. Intention-to-treat analysis revealed no benefit of intravenous heparin on outcome (mortality 5 per cent versus 11 per cent in non-heparin-treated patients, p = 0.3), hospital stay (p = 0.7) or duration of hypoxaemia (p = 0.4) (AU)

Cardio-pulmonary responses and gas exchange during exercise in adults with homozygous sickle-cell disease (sickle-cell anaemia)

Cardio-pulmonary responses and gas exchange during progressive exercise, the ventilatory response to hypercapnia and anthropometric indices were measured in twenty-two Jamiacan adults with homozygous sickle-cell disease. Their anthropometric indices and exercise performances were compared with those observed in healthy but sedentary adults in the Caribbean. The patients had long lower limbs for their height; their body fat, proportion of lean body mass as muscle and vital capacity reduced. Haemoglobin concentration ranged from 4 to 10g/100ml. Heart rate and ventilation were normal at rest. During exercise in the male patients haemoglobin concentrations below about 8g/100ml were associated with an increased demand for anaerobic metabolism. This resulted in excessive lac ticacidaemia and increased ventilation at standard oxygen uptake (hyperpnoea). The ventilation-tidal volume relationship was normal. When allowance was made for differences in body muscle, anaemia did not appear to affect the heart-rate response to exercise. Hyperventilation with respect to carbon dioxide output, increased alveolar-arterial oxygen-tension gradients and abnormal deadspace ventilation during exercise indicated a pulmonary perfusion disturbance with mixed venous shunting. The most likely basis for this disorder was considered to be the sickling phenomenon. Arterial hypoxaemia produced by the pulmonary shunt probably accounted for some of the exercise hyperpnoea, partly by increasing the chemoreceptor drive and partly by encouraging lacticacidaemia. Reduced arterial carbon dioxide tensions and bicarbonate concentrations had lowered the threshold and increased the sensitivity of the ventilatory response to carbon dioxide as measured by rebreathing. Increased chemosensitivity was not thought to have contributed towards the exercise hyperpnoea since arterial carbon dioxide tensions were below the threshold value for ventilatory drive. Exertional dyspnoea in sickle-cell disease was attributed to the combination of hyperpnoea and reduced maximum breathing capacity (MBC) owing to small lung volumes. The fraction of (MBC) used at standard work was therfore abnormally large, and the increased ventilatory effort produced a sensation of breathlessness in some patients (Summary)

Causes of death in tetanus: a clinical study of 55 patients - abstract

Since January 1965, 55 patients have been treated in the recovery and intensive therapy unit of U.H.W.I. 12 deaths have occurred - mortality rate 21.8 percent. Based on experience gained in this series and using illustrative rate 21.8 percent. Based on experience gained in this series and using illustative case reports certain aspects regarding causes of death and their prevention are discussed. Deaths in early tetanus almost invariably are related to severe anoxia or possibly due to an increased susceptibility to lesser degrees of anoxia. There have been no early deaths in patients managed in this unit but reference is made to other, essentially preventable, deaths occurring prior to admission. The life threatening complications encountered later in the disease are more varied and have included severe respiratory depression, anoxia and acidosis, exhaustion, hyperpyrexia, infection, pulmonary emboli and iatrogenic difficulties associated with tracheostomy and mechanical ventilation. The necessity for intensive therapy facilities in severe tetanus is emphasized. It is possible that many deaths in this group are also preventable. In 3 patients measurements have been made of ventilatory, acid base and oxygen transport parameters at intervals during their illness. Results are given and significance discussed. In conclusion the precipitating causes of death in this series are clinically obvious even if the exact mechanisms are not clear. We have seen little evidence of the previously described syndrome of fulminating intoxication with myocardial or brain stem involvement. We agree with others who state that the successful outcome in a previously health patient who develops tetanus should rarely be in doubt providing the patient has received ideal treatment based on the well- recognized principles of intensive therapy(AU)

Bizarre complications of whooping cough

Neurological complications following whooping cough are rare. A case report involving a seven year old girl in which blindness and recurrent bilateral paralysis of the limbs occurres with slow recovery after treatment with steroids. It is postulated that these neurological complications were due to haemorrhage associated with edema and possibly anoxia. (AU)

Prevention and treatment of some anaesthetic accidents

An account is given of some of the principles complications of anaesthesia with appropriate prophylaxis, treatment and prognosis. The importance of hypoxia, as a factor in serious accidents, is emphasized (AU)