Mediastinitis in heart transplantation.

Between March 1985 and December 1991, mediastinitis developed in 12 of 420 cardiac transplantation patients (2.8%). The mortality rate in this group of patients was 8.3% (1/12). Actuarial survival (1 year, 75%; and 5 years, 65%) was not significantly different from that of the group without mediastinitis (1 year, 88%; and 5 years, 75%). A higher percentage of the patients in the group with mediastinitis were listed as UNOS status 1 (50% versus 35%) and had a history of previous sternotomies (58% versus 44%). The presentation of mediastinitis was typical. Computed tomographic scanning with or without aspiration was a valuable adjunct in the diagnosis of mediastinitis. Induction immunotherapy with minimal steroids in the perioperative period was used in all patients. This may contribute to the patients' ability to mount an appropriate and effective response to infection, permitting earlier diagnosis. The debridement irrigation technique used in 8 of 12 patients had a low success rate of 33%, whereas the debridement muscle flap technique used in 4 of 12 was 100% successful in eliminating infection.     

Thermal injury in pregnancy--the neglected tragedy

Thermal injury sustained during pregnancy presents special management problems for the gravid woman and her unborn child. Because of the reported high morbidity and mortality and lack of available data in South Africa, a multicentre retrospective review was undertaken by five burn centres. Thirty-three patients (average age 25,7 years) with mean 30% (range 1-80%) total body surface area burn were assessed. A review of the clinical material led to the following observations and conclusions. Pregnancy does not influence maternal outcome after thermal injury and maternal survival is usually accompanied by fetal survival in the absence of significant maternal complications. Maternal survival is less likely if the burn wound exceeds 50% total body surface area. Thermal injury does increase the risk of spontaneous abortion and premature labour, and fetal survival depends on fetal maturity. Early obstetric intervention is only indicated in the gravely ill patient where complications (hypoxia, hypotension, sepsis) jeopardize the life of a viable fetus. The mode of delivery should be determined by obstetric considerations.     

Patch clamp studies on the kinetics and selectivity of N-methyl-d-aspartate receptor antagonism by memantine (1-amino-3,5-dimethyladamantan)

Memantine (1-amino-3,5-dimethyladamantan) was tested as an antagonist of N-methyl-d-aspartate (NMDA) receptors on cultured superior collicular and hippocampal neurones using the patch clamp technique and its actions were compared to those of Mg²⁺ ions, ketamine, dextrorphan, dextromethorphan, phencyclidine and dizocilpine (MK-801). Memantine (2–33 μM) concentration-dependently antagonized responses to NMDA 100 μM with an IC₅₀ of 2.92 ± 0.05 μM. In contrast, current responses to (S)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (l-AMPA 50–100 μM) and γ-amino butyric acid (GABA 10 μM) were unaffected by Memantine 8 μM. Memantine 8 μM caused a non-parallel shift of the NMDA concentration-response curve to the right in a manner indicative of uncompetitive open channel block. The effects of memantine were similar to ketamine in that both antagonists were weakly use- and strongly voltage-dependent. In contrast, MK-801, phencyclidine and dextrorphan showed much slower kinetics that was reflected in their marked use- and weaker voltage-dependency. The antagonistic effects of memantine were not reversed by increasing concentrations of glycine (0.1–100 μM) ruling out the possibility of an interaction of memantine with the strychnine-insensitive glycine modulatory site associated with the NMDA receptor-channel complex. Memantine (1–100 μM) also selectively antagonized responses to NMDA (40 μM) in the cortical wedge preparation with IC₅₀ of 12.9 ± 1.5 μM.     

THE CASE AGAINST OPEN NECK BIOPSY

Many patients present with lateral neck lumps due to benign or malignant conditions, and they may be difficult to differentiate clinically. It is detrimental to perform an open neck biopsy on a patient with a cancer originating from the head and neck region (upper aerodigestive tract or skin) prior to definitive treatment. The biopsy interferes with the assessment and management of the neck, increasing morbidity. It may also decrease curability and perhaps induce fungation. A protocol to avoid the need for an open biopsy, using fine needle aspiration cytology and a thorough examination of the upper aerodigestive tract is recommended. The authors also recommend combined radical radiotherapy and surgery for the patient who has had an open biopsy. A thoughtless biopsy is both needless and harmful.     

Empirical treatment without bronchoscopy for Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome.

An empirical approach to treating Pneumocystis carinii pneumonia was adopted in a prospective study of 73 men with antibodies to human immunodeficiency virus 1 (HIV-1) presenting with respiratory problems. At presentation 49 patients (group 1) were thought to have a history, findings at clinical examination, chest radiograph, and arterial blood gas tensions typical of pneumocystis pneumonia, and empirical treatment was begun immediately. Twenty four patients (group 2) were thought to have features not typical of pneumocystis pneumonia. All patients were subsequently referred for bronchoscopy to determine the diagnosis. In group 1 four patients were excluded from the analysis because bronchoscopy was not possible. Of the remaining 45, 42 had pneumocystis pneumonia, which was diagnosed at bronchoscopy in 40, and on the basis of the clinical response to co-trimoxazole in two who had negative results from investigations. Of the three patients without pneumocystis pneumonia, one patient with lymphoid interstitial pneumonitis and Branhamella catarrhalis infection would have failed to respond to empirical treatment. The other two had multiple bacterial pathogens at bronchoscopy; one already had Kaposi's sarcoma and the other would have been misdiagnosed as having AIDS. In group 2 a specific diagnosis was made at bronchoscopy in 21 cases, including pneumocystis pneumonia in seven (all had atypical chest radiographs). In three cases no diagnosis was made and spontaneous recovery occurred. Adopting an empirical approach to treatment for typical pneumocystis pneumonia (group 1) led to the correct treatment in 43 of 45 cases (95%) and would have saved 44 of the 45 of bronchoscopies in this group. Adopting an empirical approach would have caused one patient to be misdiagnosed as having AIDS. Overall, 44 out of 69 bronchoscopies (64%) would have been saved; the specificity for the diagnosis of pneumocystis pneumonia was 85% and the sensitivity was 85%. Adopting an "empirical" treatment policy for typical pneumocystis pneumonia will cause a large reduction in the number of "high risk" bronchoscopies performed.     

Cholinergic amacrine cells of the chicken retina: a light and electron microscope immunocytochemical study

Cholinergic amacrine cells of the chicken retina were detected by immunohistochemistry using an antiserum against affinity-purified chicken choline acetyltransferase. Three populations of cells were detected: type I cholinergic amacrine cells had cell bodies on the border of the inner nuclear and inner plexiform layers and formed a prominent laminar band in sublamina 2 of the inner plexiform layer, while type II cholinergic amacrine cells had cell bodies in the ganglion cell layer, and formed a prominent laminar band in sublamina 4 of the inner plexiform layer. Type III cholinergic amacrine cell bodies were located towards the middle of the inner nuclear layer, and their processes were more diffusely distributed in sublaminas 1 and 3-5 of the inner plexiform layer. Type I and type II cells were present at densities of over 7000 cells/mm2 in central areas declining to less than 2000 cells/mm2 in the temporal retinal periphery. The cells were organized locally in a non-random mosaic, with regularity indices ranging from 3 peripherally to over 5 centrally. Neither at the light nor electron microscopic levels was a lattice of cholinergic dendrites of the kind reported by Tauchi and Masland [J. Neurosci. 5, 2494-2501 (1985)] detectable. Within the two prominent dendritic plexuses, a major feature of the synaptic interactions of the type I and type II cholinergic cells was extensive synaptic interaction between cholinergic processes. Apart from this, there was little, if any, input to cholinergic processes from non-cholinergic amacrine cells, but there was input from bipolar cells. Output from the cholinergic amacrine cell processes was directed towards non-cholinergic amacrine cells as well as other cholinergic amacrine cells, and ganglion cells.     

Diabetes care in general practice: an approach to audit of process and outcome.

As a chronic condition in which the major adverse outcomes only occur after many years, diabetes poses special problems for continuing medical audit. The feasibility of continuous audit of process and outcome in diabetes care has been tested in four general practices with organized diabetes care in Newcastle upon Tyne. For all patients with previously diagnosed non-insulin dependent diabetes, the data already collected according to published protocols were assembled into a single database. The time and resource costs of this exercise, together with measures of process, complications, risk factors, and metabolic outcomes were analysed. Data were successfully collected at minimal cost where structured records were completed. Recommended processes had been completed in a high percentage of patients, adverse patient outcomes were limited, and metabolic output measures not unsatisfactory. Nevertheless, attention has been directed to areas where care could be improved. Continuing diabetes audit in primary health care is feasible and helpful, and can use the same measures as in the hospital setting.