Cysteine protects Na,K-ATPase and isolated human lymphocytes from silver toxicity

Metal-binding proteins are important components of retroviruses such as human immunodeficiency virus (HIV). Therefore, metals could be used as antiviral agents. However, most metals are toxic for humans with the exception of silver which is toxic only to prokaryotic cells and viruses. In addition, HIV infection causes a decrease in body cysteine. We formed a complex of silver and cysteine, named silver-cysteine. Healthy human lymphocytes were incubated with silver-nitrate or silver-cysteine. Negligible cell survival was seen at 50 microM silver-nitrate. However, in presence of 1 mM cysteine, the viability remained unaffected up to 1 mM of silver. Further, silver inhibition of isolated Na,K-ATPase was easily reversed by cysteine. Thus, non-toxic silver-cysteine could be used as an anti-viral and cysteine-replenishing agent.

A peptidergic component to vagally induced tracheal vasodilation in the dog

The purpose of the study was to determine the extent that peptidergic afferent and efferent pathways contribute to vagally induced vasodilation in the trachea of the dog. The change in vascular resistance of the tracheal branch of the cranial thyroid artery and the trachealis responses were determined in 28 anesthetized, paralyzed, and mechanically ventilated dogs. After propranolol (2 mg/kg) and phentolamine (1.5 mg/kg), stimulation of the superior laryngeal nerves (NS; 15 Hz, 7 V, 2 ms, 30 s) caused a decrease in vascular resistance of 11.7 +/- 0.8% and a tracheal contraction of 5.2 +/- 4.7 cmH2O. Atropine (1.5 mg/kg) reduced the fall in vascular resistance to 4.7 +/- 0.8% (P less than 0.01), whereas tracheal contraction was abolished. Thiorphan (1.5 mg), a neutral endopeptidase inhibitor, augmented the decrease in vascular resistance (8.8 +/- 0.6%; P less than 0.01) to NS. After hexamethonium (0.5 mg/kg), NS still caused a small decrease in TVR (2.9 +/- 0.9%; P less than 0.05), which was abolished by capsaicin. In atropinized dogs, capsaicin reduced the fall in vascular resistance after NS; the residual vasodilation was virtually abolished by hexamethonium. Acetylcholine (10(-3) mg/kg) decreased vascular resistance (15.7 +/- 3.0%), and the effect was abolished by atropine. We conclude that there is noncholinergic nonadrenergic vagally induced tracheal vasodilation that is peptidergic. The peptidergic vasodilation appears to be mediated by both afferent and efferent pathways.

Increased lipid peroxidation in patients on maintenance hemodialysis

Lipid peroxidation products, lipid hydroperoxide and malonaldehyde were measured in the serum of patients on maintenance hemodialysis and compared with values obtained from a group of healthy controls. Dialysis patients had significantly elevated levels of lipid peroxidation products (12.9 +/- 1.9 vs. 9.3 +/- 1.3 nmol/ml, mean +/- SD, patients vs. controls, p less than 0.0001). In contrast, the serum transferrin level was significantly lower in the dialysis patients (217 +/- 71 vs. 290 +/- 50 mg/dl, patients vs. controls, p less than 0.0002). Compared to normal controls HDL cholesterol was lower (40 +/- 11 vs. 53 +/- 8, p less than 0.0001) and triglycerides were higher (206 +/- 103 vs. 142 +/- 64, p less than 0.007) in the patient group. The patient group was then divided on the basis of using polysulfone or cupraphane dialyzers. Patients using polysulfone dialyzers had lower levels of 2-thiobarbituric acid-reactive substances (12.3 +/- 0.9 vs. 13.6 +/- 2.1, polysulfone vs. cupraphane, p = 0.05), and higher transferrin concentrations (248 +/- 84 vs. 194 +/- 37, p = 0.03). Thus, in patients on maintenance hemodialysis there was evidence for accelerated lipid peroxidation. This abnormality was more marked in patients using traditional cupraphane dialyzers. The mechanism for this observation remains unclear.

Alpha thalassaemia in Saudis

The alpha-thalassaemias are group of inherited anaemias. Their severity is known to increase with the number of alpha-globin genes deleted. Employing different types of restriction enzymes, we found that alpha-thalassaemia-2 are more common than held previously. On the basis of our results we also anticipate that the haplotype alpha alpha alpha anti3.7/ occurs at a higher frequency.

The role of extracellular medium components and specific amino acids in the cytotoxic response of Escherichia coli and Chinese hamster ovary cells to hydrogen peroxide

A concentration of H2O2 resulting in mode one killing of Escherichia coli is more toxic when exposure to the oxidant is performed in complete medium (K medium), as compared to a saline (M9 salts). Inorganic salts (MgSO4 and CaCl2), thiamine or glucose, when added separately, or combined, to M9 salts had no effect on the cytotoxic response to H2O2. In contrast, the lethality of the oxidant was highly dependent on the presence of the amino acids in the incubation medium. The addition of glucose further enhanced this response. Among the seventeen amino acids which are present in the complete amino acid mixture, only two, i.e. L-histidine and L-cystine, were found to increase the toxicity of H2O2. Again, glucose augmented this response. The effect of these amino acids on the growth inhibitory action of hydrogen peroxide was also tested in Chinese Hamster Ovary cells. It was found that L-histidine was capable of increasing the toxicity of the oxidant whereas all the other amino acids did not affect the toxicity of the oxidant. Glucose only slightly augmented this effect of L-histidine. DNA single strand breakage produced by H2O2 was increased by L-histidine and was not significantly modified by the other amino acids. DNA double strand breakage was also shown to occur in cells exposed to H2O2-L-histidine, and this effect was independent on the presence of glucose. These results demonstrate that the cytotoxic response of bacterial and mammalian cells to challenge with H2O2 is highly dependent on the composition of the extracellular milieu.(ABSTRACT TRUNCATED AT 250 WORDS)

Total hip arthroplasty for protrusio acetabuli: a 3- to 9-year follow up of the Heywood technique

Thirty-five total joint arthroplasties (34 patients) were performed in patients who had protrusio acetabuli. Twenty-nine percent of the patients had acetabular protrusio of grade I, while 71% had grade II and grade III protrusio. The mean follow up was 4 years (range: 3 to 9). Cemented acetabular components were used in 11 hips; 24 hips received an uncemented porous coated acetabular component. The patient evaluations included preoperative and postoperative Harris Hip Ratings and standard radiographs. In all cases, the medial wall defect was reconstructed with the solid autogenous femoral head as described by Heywood. The mean preoperative Harris Hip Rating was 45 (range: 30 to 60 points), and the postoperative mean was 85 (range: 70 to 100 points). Radiographically, the preoperative protrusio measured a mean of 8.8 mm (range: 6 to 18 mm), and the mean postoperative placement of the femoral head was 10 mm lateral to Kohler's line (range: 6 to 13 mm). There were no acetabular component failures and no acetabular bone graft resorptions. All autogenous grafts were incorporated to the host radiographically by 1 year post-surgery. This study corroborates previous work which suggests that medial-placed bone grafting is not resorbed and consolidates with the host bone. We find this technique extremely useful in dealing with this technical problem.

Technical report: wire guided sialography

An improved technique for performing sialography in difficult cases is described. This is based on the passage of a cannula into the salivary duct ostium over a thin, flexible, blunt guide-wire.

Failure of oxygen radical scavengers to modify fatigue in electrically stimulated muscle

We used in situ gastrocnemius muscle of anaesthetized dogs to test the hypothesis that O2 radical production during muscle contraction contributes to fatigue. Muscle tension was measured with a force transducer and blood flow was monitored with an electromagnetic flow probe. Muscle contractions were produced by stimulating the nerve for 15 min at 20 Hz, 12 trains/min, and a duty cycle of 0.25. Three groups of seven animals were given an infusion of 0.2 mL.min-1 of either saline, low-dose oxygen radical scavengers (250 IU.mL-1 superoxide dismutase, 640 IU.mL-1 polyethylene glycol (PEG)-catalase, 0.25 mg.mL-1 deferoxamine, and 0.1 mg.mL-1 oxypurinol), or high-dose oxygen radical scavengers (3300 IU.mL-1 superoxide dismutase, 6600 IU.mL-1 PEG-catalase, 2.5 mg.mL-1 deferoxamine, and 0.1 mg.mL-1 oxypurinol). Blood flow and vascular resistance of the gastrocnemius muscle during stimulation did not differ among groups. After 15 min of stimulation, the developed tension (represented as a percentage of initial tension developed) was 66 +/- 7% in the saline treated group, 70 +/- 6% in the low-dose group, and 70 +/- 4% in the high-dose group. The change in tension during recovery was not significant in the control or low-dose groups. However, there was partial recovery in the high-dose group. In conclusion, in this preparation, oxygen radical scavengers did not delay the development of decreased muscle tension.

Receptor sub-types involved in responses of Purkinje cell to exogenous excitatory amino acids and local electrical stimulation in cerebellar slices in the rat

The effects of the NMDA receptor antagonist, 2-amino-5-phosphonovalerate (APV) and non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) on responses of Purkinje cells to exogenous excitatory amino acids and to electrical stimulation of the parallel fibres, were investigated in slices of the cerebellum of the rat. Glutamate, aspartate, kainate and quisqualate all induced excitation of Purkinje cells. Responses to kainate and quisqualate were blocked by CNQX (10 microM) but not by APV (10 microM). N-Methyl-D-aspartate induced biphasic excitatory-inhibitory responses, both components of which were blocked by APV but not by CNQX. The inhibitory component was less sensitive to blockade by APV but was totally blocked by bicuculline, the GABAA receptor antagonist. Parallel fibre stimulation most commonly induced inhibition of Purkinje cells, with or without preceding excitation. This inhibition was blocked by APV and excitatory responses were often revealed. A less commonly-observed predominantly excitatory response was blocked by CNQX but not by APV and inhibition tended to be revealed. These data suggest that parallel fibre-Purkinje cell synapses possess non-NMDA postsynaptic receptors, while the parallel fibre-inhibitory interneuron synapses possess functional NMDA receptors.

Magnetic resonance imaging of the knee

Magnetic resonance imaging of the knee was the first successful application of this technique to the articular system. The advantages of magnetic resonance imaging over arthrography include its noninvasive nature, the ability to evaluate the knee in multiple planes without patient repositioning, the absence of ionizing radiation, the capacity to evaluate the joint even in the presence of joint effusion, and the ability to examine the inner structure of the meniscus as well as its surface. Although magnetic resonance imaging initially was used to study the menisci and cruciate ligaments, the technique has been expanded to include the evaluation of various conditions and all the structures of the knee joint and surrounding soft tissues.

Evaluation of the roll over test as predictor of gestational hypertension in African women

Fifty-six primigravid women at 28-32 weeks gestation were studied prospectively to assess the roll over test (ROT) as a predictor of gestational hypertension in African women. Blood pressures were measured continuously in the supine and left lateral positions using an automated accutor machine. ROT was positive in only two women (3.6%). These two women later developed gestational hypertension but so did 18 others who had negative ROT. Measures that may be useful in increasing the predictive value of the ROT in these women are suggested.

Modulation of GABA-mediated inhibition in rat cerebellar slices by benzodiazepine receptor ligands

1. Extracellular recordings were made from the Purkinje cell layer of rat cerebellar slices. Compounds were perfused over the slice and bipolar stimulating electrodes placed in the external layer of the slice close to the recording electrode. 2. Stimulus-evoked inhibition of Purkinje layer cell activity was sensitive to bicuculline methiodide and picrotoxin, suggesting it was gamma-aminobutyric acid (GABA) mediated. The benzodiazepine ligands RU 32007 and Ro 19-0528 reversibly increased the period of inhibition, as did pentobarbital. This benzodiazepine effect was antagonised by Ro 15-1788. 3. Five inverse agonists all reduced the period of stimulated inhibition and this effect was reversed by Ro 15-1788, suggesting the involvement of benzodiazepine receptors. 4. It is concluded that this system provides a convenient physiological and possibly quantitative model for studying the action of benzodiazepine receptor ligands.

Does standing up improve the predictive value of the supine pressor test for gestational hypertension?

Fifty-six primigravid women at 28-32 weeks' gestation were studied prospectively to compare the roll-over test with the stand-up pressor test in the prediction of gestational hypertension. Blood pressures were measured in the different positions continuously using an automated machine. Twenty patients developed gestational hypertension; two of these were accurately predicted by roll-over test and six by stand-up pressor test (P less than .001). However, there was no significant difference between the tests in the rates of false negatives, specificity, and negative and positive predictive values. Concomitant measurement of blood pressures in the standing position may increase the sensitivity of the roll-over test for the prediction of gestational hypertension.

Quantitative analysis of gamma-aminobutyric acid (GABA) receptors of Purkinje cell layer from rat cerebellar slices

1. Extracellular recordings were made from Purkinje cell layer of rat cerebellar slices. Cell activity was sensitive to both magnesium and manganese ions. 2. Glutamic and aspartic acids both excited cell activity while gamma-aminobutyric acid (GABA), muscimol, taurine, beta-alanine and delta-aminolaevulinic acid all inhibited activity. 3. The sensitivity to GABA varied with depth while no such effect was observed with muscimol. 4. Bicuculline methiodide, picrotoxin and pitrazepin blocked the action of muscimol with pA2 values of 5.92, 5.97 and 5.71 respectively. 5. The benzodiazepines flurazepam and RU 32007 both potentiated the GABA inhibition and this potentiation was blocked by Ro 15-1788, a benzodiazepine antagonist.

Isradipine in Asian patients with hypertension

Isradipine, a new calcium antagonist, was administered to 51 Pakistani patients with hypertension (36 women, 15 men; mean age 47 years) over an 8-week period. Mean sitting systolic, and sitting and standing diastolic blood pressure was significantly reduced, and mean standing systolic blood pressure tended to decrease. Laboratory values, and both sitting and standing heart rates were not significantly affected by isradipine treatment. At the end of 8 weeks, 41.2% of patients were receiving isradipine 1.25mg twice daily, and 58.8% were receiving 2.5mg twice daily. Isradipine was found to be effective and well tolerated in Pakistani patients with mild to moderate hypertension.

Chemosuppression of malaria by the triple combination mefloquine/sulfadoxine/pyrimethamine: a field trial in an endemic area in Malaysia

Malaria, particularly that due to chloroquine-resistant Plasmodium falciparum, which requires management with antimalarial drugs capable of protecting against multiresistant strains, has emerged in Malaysia. A study was carried out to assess the efficacy and tolerability of 2 dosages of mefloquine/sulfadoxine/pyrimethamine (MSP; RO 13-5112) compared to Fansidar in a malaria endemic area. 914 subjects in 3 random groups were studied. Occurrence of malaria was assessed both clinically as well as by blood films. Plasma drug levels were also measured. The results showed that the low dose of MSP was completely effective in suppressing parasitaemia. 2.7% of the study population reported adverse drug reactions, the lowest incidence being in subjects on the low dose; their blood chemical profiles were also the least affected. The plasma levels of pyrimethamine and sulfadoxine achieved in the low dose group were slightly higher than expected, but there was no significant difference in bioavailability. The study showed that, for chemoprophylaxis, a low dose of MSP provided effective protection with minimal side effects.

Penetrating atherosclerotic ulcers of the thoracic aorta

Penetrating ulcer of the thoracic aorta is defined as an atherosclerotic lesion of the descending thoracic aorta with ulceration that penetrates the internal elastic lamina, allowing hematoma formation in the media. There is controversy whether this lesion differs from classic acute type III aortic dissection, based on its location, radiographic findings, natural history, and recommended therapeutic approach. Of 47 patients with a diagnosis of aortic dissection seen at our hospital during a 2-year period, five patients had clinical and radiographic findings of penetrating ulcer. Each of the five patients had characteristic computerized tomographic (CT) findings and two patients had angiographic confirmation. In all patients CT showed subintimal hemorrhage, aortic wall enhancement, absence of a double lumen, and contrast extravasation through the ulceration. In both patients who underwent angiography, ulceration, subintimal hematoma, and absence of a false lumen were demonstrated. The clinical presentation in four patients simulated acute aortic dissection or expanding thoracic aneurysm. The other patient, who was normotensive, did not have symptoms referable to the thoracic aorta but was studied because of an abnormal chest x-ray film. None of these five patients required surgical intervention. All five patients were alive and free of symptoms at 6 months, 8 months, 14 months (two patients), and 30 months after the original diagnosis. Follow-up CT scans in four patients showed resolution of subintimal hematoma and some dilatation of the lumen but no progression to rupture or aneurysm. Other authors stress the importance of differentiating symptomatic penetrating atherosclerotic ulcers from acute type III aortic dissection because of the higher incidence of rupture of penetrating ulcers and therefore recommend early surgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Host response to autologous endothelial seeding

Dacron and expanded polytetrafluoroethylene grafts, seeded with autologous venous endothelial cells at the time of implantation, subsequently develop endothelial linings. However, it has not been shown whether the endothelial cells in these linings are derived from the seeded cells, or whether the seeding process itself stimulates host endothelial cells to proliferate and cover the grafts. As a first step in testing this hypothesis, bilateral end-to-side aortoiliac expanded polytetrafluoroethylene grafts with an internal diameter of 6 mm, an internodal distance of 22 microns, and an average length of 9.2 cm were placed in 10 adult mongrel dogs weighing 20 to 25 kg; the aorta was ligated just distal to the origin of the grafts. The graft on one side, chosen at random, was seeded with autologous endothelium that was harvested by enzyme single-stage technique from external jugular veins; the other side was not seeded. After 4 weeks the animals were anesthetized and heparinized, and the grafts were fixed by perfusion in vivo with 2.5% glutaraldehyde solution before they were removed. Both grafts occluded in two animals, and both grafts were patent in five animals. In two animals the seeded grafts were open and the unseeded grafts were occluded. In one the seeded graft was occluded and the unseeded graft was patent. There was no significant difference in clot-free surface area between seeded (29% +/- 18%) and unseeded (31% +/- 11%) grafts. Scanning electron microscopy showed the presence of an endothelial monolayer that averaged 39% +/- 20% and 36% +/- 26% coverage, respectively, in the clot-free midgraft portions of all seeded and unseeded patent grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Interposition of extensor digitorum tendon in distal radius fracture mimicking a compartment syndrome

A 14-year-old boy sustained a dorsally displaced Salter-Harris Type II fracture of the distal radius. A single attempt at closed reduction failed. After this closed reduction, the patient was unable to passively or actively extend or flex his fingers. He had increasing pain and compartment pressures were abnormally elevated. Dorsal fasciotomy was done, and during the open reduction, entrapment of the dorsal extensor retinaculum and extensor digitorium communis within the fracture was found. After removal of these structures, fracture reduction was easily accomplished and his fingers had a full range of motion. Postoperative recovery was uneventful.

A user evaluation of four Kodak Ektachem slide assays

Evaluations of magnesium, theophylline, creatinine, and creatine kinase isoenzyme MB assays by the Kodak Ektachem multilayer-film technique are reported.