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Biomedical subjects

M King

Publications and source records attributed to M King.

At least 235 records · Page 13Linked to original sources
PubMed1993

Gram-negative meningitis and chronic constipation: an unusual presentation of caudal regression syndrome.

Congenital malformations may present as meningitis caused by enteric organisms, but this is extremely rare and occurs almost exclusively in the paediatric population. We report an unusual case of a young man with chronic constipation presenting with spontaneous Gram-negative meningitis due to an underlying congenital spinal malformation known as the caudal regression syndrome.

Abnormalities, Multiple↗
PubMed1993

Amiloride inhalation therapy in cystic fibrosis. Influence on ion content, hydration, and rheology of sputum.

Amiloride inhalation as treatment for cystic fibrosis (CF) lung disease has been shown in independent studies to increase mucus clearance by ciliary and/or cough action and to retard the decline in lung function. It is hypothesized that amiloride therapy decreases the excess sodium and water absorption that is a characteristic of CF airway epithelium and that it leads to an improvement in the rheologic properties of mucus favoring airway mucus clearance. The aim of this study was to investigate whether amiloride treatment (5 x 10(-3) M amiloride in one-third normal saline four times a day) would change sputum electrolyte composition in patients with CF after 25 wk of therapy as compared with placebo (one-third normal saline), and whether appropriate changes in sputum water content and rheologic properties would accompany any changes in electrolyte composition. Sputum samples were obtained from six patients with CF undergoing amiloride therapy, using the dental cotton protection technique to avoid salivary contamination. The samples were stored at -80 degrees C until analyzed. For electrolyte analyses an aliquot of the sputum (minimum, 30 mg) was analyzed with ion-selective electrodes for sodium and potassium, and a chloride meter was used to measure chloride content. Chronic (25-wk) amiloride therapy increased significantly the sputum sodium (94.8 +/- 16.4 to 121.4 +/- 15.4 mmol/L, p = 0.001) and chloride (64.4 +/- 11.8 to 77.2 +/- 8.0 mmol/L, p = 0.10) content when compared with 25 wk of saline treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1993

Sulfated glucuronyl glycolipids and gangliosides in the optic nerve of humans.

Pathologically delayed visual evoked potentials may be present in patients with neuropathy associated with IgM M-proteinemia, which is directed against myelin-associated glycoprotein and sulfated glucuronyl glycolipids (SGGLs), but there are no reports of these antigens in the optic nerve. We recently examined human optic nerve and occipital lobe tissues for the occurrence of SGGLs using the technique of immunostaining on thin-layer chromatographic plates and found them in the optic nerve, but not the occipital lobe. SGGLs in the optic nerve may represent target antigens for CNS involvement by the M-protein in patients with neuropathy. We also studied the ganglioside composition of the optic nerve and found it different from that of the brain. Human optic nerve is characterized by an abundance of the b-series gangliosides, including GD1b, GT1b, and GQ1b. GD1a, which is usually a major component of brain gangliosides, is only a minor species of the optic nerve ganglioside fraction.

Chromatography, Thin Layer↗
PubMed1993

Cooperation within--the patient care team advantage.

As the demand for post-hospital health care increases, one home care agency has developed a referral process that makes the transition from hospital to home as smooth as possible for both patients and health care professionals.

Aftercare↗
PubMed1993

Purchasing palliative care: availability and cost implications.

This paper reports on a survey of the availability of palliative care in Scotland, in the context of the internal market introduced as part of the NHS reforms. It is based on a survey of both the cost and availability of such service, with a discussion of the implications of this information for purchasers of palliative care.

Data Collection↗
PubMed1993

Ferret tracheal mucus rheology, clearability and volume following administration of substance P or methacholine.

We studied the effects of substances P administration on tracheal mucus viscoelasticity, water content, clearability and secretion rate. Six neutered adult male ferrets (weight 1.1-1.5 kg) were studied, on four occasions each. They were anaesthetized with ketamine and xylazine, and intubated shallowly. Control mucus (pre- and post-Ringer instillation) was compared with the mucus obtained following instillation of 200 microliters of 10(-6), 10(-5), and 10(-4) M substance P (SP), and 10(-4) M methacholine chloride as a reference. Tracheal mucus was collected by inserting a soft-bristled cytology brush to the level of the carina, and leaving it in contact with the mucosa for 30 min. After withdrawing the brush, the adherent mucus was quickly scraped off and layered with paraffin oil to prevent evaporation. The mucus was analysed for viscoelasticity by magnetic rheometry and solids content by evaporation to dryness. Mucus transportability was assessed by comparison with model gels, and also by means of the frog palate assay, which indicates how well mucus is cleared by normal ciliary action. There was a dose-related increase in mucus volume, and a dose-related decrease in mucus viscosity and elasticity, with substance P administration. Mucus transportability increased with both substance P and methacholine. The effects of 10(-4) SP and methacholine were comparable in terms of viscoelasticity and volume; with both methacholine and SP, there appeared to be an additive effect. The mucus solids content did not correlate with the viscoelastic changes for SP administration, whereas it did for methacholine. These observations suggest that the hypersecretion induced by these two agents might involve different pathways.

Analysis of Variance↗
PubMed1993

Rheology of mucus and transepithelial potential difference: small airways versus trachea.

The transfer of water across the airway epithelium is closely related to the transepithelial potential difference (PD). Thus, PD should be directly involved in the regulation of airway intraluminal water content and, by extension, mucus rheology. Experiments by Boucher and co-workers (J Appl Physiol, 1980; 48: 169; and 1981; 51: 706) indicated that the values of PD in the small airways of dogs were considerably lower than in the trachea or mainstem bronchus. This fact suggests that water is increasingly removed from the airway lumen in the cephalad direction, and provides a possible mechanism whereby airway flooding is avoided as the total airway cross-section diminishes mouthward. We investigated this possibility by collecting and analysing mucus from the small airways and trachea of anaesthetized dogs and comparing our findings with measurements of PD. Mucus was collected on a cytology brush placed against the wall of the airway. Tracheal samples were taken from the lower lateral or anterior trachea, while small airway samples were taken from a 6th or 7th generation bronchus, chosen at random from either side. Measurements of PD were made at comparable sites. The mucus was analysed for its viscoelastic properties using the magnetic microrheometer technique. PD in the 6th-7th generation bronchus was significantly less than in the lower trachea (4.1 +/- 1.3 vs 17.2 +/- 7.1 mV). The rigidity of mucus collected from the small airways (log mechanical impedance (G*) at 100 rad.s-1) was significantly less than in the trachea (2.81 +/- 0.22 vs 3.01 +/- 0.29).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

The effects of five years of nocturnal cuirass-assisted ventilation in chest wall disease.

We investigated the long-term effectiveness of cuirass-assisted ventilation, and examined whether mortality and morbidity could have been predicted at the time of admittance. Twenty five patients were commenced on nocturnal cuirass-assisted ventilation between 1983 and 1985, 10 with scoliosis or kyphosis, 8 with a thoracoplasty and 7 with neuromuscular disease. Mean pretreatment vital capacity was 30% of predicted, and arterial carbon dioxide tension (Paco2) was 8.2 kPa (62 mmHg). Fifteen patients were alive 5 yrs later. Two had discontinued assisted ventilation, both dying soon afterwards, and three had been changed to intermittent positive pressure ventilation. Survival could not have been predicted from age, severity of disease, lung volumes or arterial blood gases at presentation. Paco2 in the survivors had risen from a mean of 6.1 kPa (46 mmHg) after one year to 6.8 kPa (52 mmHg) after 5 yrs (p < 0.05), but remained significantly less than at presentation. There were no significant change in arterial oxygen tension (Pao2), lung volumes, respiratory muscle strength, haemoglobin, right heart failure, exercise tolerance, mental function and symptom scores after 5 yrs, compared to after 1 yr. The median amount of time spent in hospital declined from 15 days per patient in the first year after initial discharge with cuirass-assisted ventilation, to between 3-5.5 days per patient in subsequent years. We conclude that nocturnal cuirass-assisted ventilation has a role in long-term management of patients with neuromuscular and skeletal chest wall disorders. A randomized comparison with nasal intermittent positive pressure ventilation is now indicated.

Adolescent↗
PubMed1992

Biocompatibility of the Vascugraft: evaluation of a novel polyester urethane vascular substitute by an organotypic culture technique.

To evaluate the biocompatibility of chemically and structurally modified polyurethane elastomers for use as blood vessel replacements, small squares of vascular prostheses were cultured in direct contact with endothelium from chick embryo aorta using an organotypic culture assay. The polyurethane materials tested were: Vascugraft (fibrous, open pore structure); commercial Hydrophilic Mitrathane prosthesis (high porosity, smooth surface, non-permeable, closed pore structure); experimental hydrophobic Mitrathane (less porosity but a fibrous, open pore structure, similar to Vascugraft). The commercial expanded polytetrafluoroethylene prostheses Impra and reinforced GORETEX were included as controls on account of their extensive clinical application in the femoropopliteal position. After 5 d incubation at 37 degrees C biocompatibility was assessed in terms of average area of migrating cells on the biomaterial, total number of cells surrounding the explant and level of adhesion between the cells and the biomaterial. The Vascugraft prosthesis promoted the growth of a continuous monolayer of cells on its surface. This behaviour was equivalent to Impra and reinforced GORETEX materials in terms of cell density and area of cell migration but appeared to be superior for cell adhesion. From a second series of cell culture tests, in which the extractables leached from the biomaterials were added to the nutrient medium, it was concluded that none of the biomaterials tested released cytotoxic contaminants.

Animals↗
PubMed1992

Respiratory alterations due to urban air pollution: an experimental study in rats.

In order to assess the adverse effects of urban levels of air pollution, rats were used as biological indicators in a chronic exposure experiment. Animals were housed for 6 months in the center of São Paulo (the largest South American city) and were compared to controls kept for the same period in a clean area. Pollution levels were obtained from a State air pollution monitoring station, 200 m distant from the exposure place, which provided the levels of CO, SO2, particulates, and ozone. The animals were submitted to several tests focusing on the respiratory system, comprising pulmonary function tests, studies on mucociliary clearance and mucus rheology, histochemical evaluation of airways, bronchoalveolar lavage, and ultrastructural studies of the epithelium of the airways. Rats exposed to air pollution developed secretory cell hyperplasia in the airways, ultrastructural ciliary alterations, and a more rigid mucus, changes that caused mucociliary clearance impairment. In addition, nasal resistance and the number of inflammatory cells recovered by bronchoalveolar lavage were increased in air pollution exposed animals. The results obtained in the present investigation suggest that chronic exposure to urban levels of air pollution may cause respiratory lesions in rats.

Air Pollution↗
PubMed1992

Aortic saddle embolus presenting with transient lower extremity paresthesia.

We report the case of a 58-year-old woman who developed acute onset of bilateral lower-extremity numbness and difficulty ambulating at home. On presentation to the emergency department, however, the patient's symptoms essentially had resolved. An aortic saddle embolus was suspected based on the patient's cardiac history and the absence of distal pulses in the lower extremities. This case illustrates that even with vague or resolving complaints, a high index of suspicion should be maintained for the diagnosis of aortic saddle embolus based on the patient's medical history and on physical examination.

Aorta, Abdominal↗
PubMed1992

A dual level model for speciation by multiple pericentric inversions.

A considerable body of evidence suggests that the deleterious meiotic effects of pericentric inversions in F1 hybrids can be overcome by changes in chiasma location and various means of non-homologous pairing. Such overriding mechanisms may render pericentric inversions benign and increase the likelihood of their fixation in population isolates. It has been argued that overriding mechanisms of this type negate the involvement of pericentric inversions as reproductive isolating mechanisms in speciation. It is suggested, however, that the involvement of pericentric inversions in speciation should be considered on two levels. First, that by reducing meiotic effects in F1 hybrids, overriding mechanisms facilitate the fixation of pericentric inversions. Secondly, when contact hybridization occurs between the chromosomally derived and parental populations second-level effects may be encountered. That is, the recombinational effects of pericentric inversion differences on coadapted gene complexes (sensu Brncic, 1954, Shaw & Coates, 1983) enforce profound inviability barriers in F2 and backcross matings. In this way, multiple pericentric inversions may act as significant post-mating isolating mechanisms, whereas individual inversions with less significant second-level effects may not.

Animals↗
PubMed1992

The polyurethane foam covering the Même breast prosthesis: a biomedical breakthrough or a biomaterial tar baby?

Because controversy continues to surround the implantation of the polyurethane foam-covered Même breast prosthesis, in vitro experiments were conducted to determine: (1) whether the polyurethane foam contains extractable toluene diamine isomers (TDAs), and (2) whether the polyurethane foam releases TDAs on exposure to mild hydrolytic conditions. Results confirmed the presence of extractable TDAs and other impurities in the foam covering the unused Même prosthesis, and that the concentrations of these impurities could be significantly reduced by washing the foam in a regular detergent. This washing step was omitted from the manufacturer's production process. Furthermore, on exposure to mild alkalis, the foam exhibited significant degradation, rapid fragmentation, loss of mechanical strength and physical integrity, as well as the release of additional TDAs. Because of the potential long-term risks associated with the release of TDAs in vivo, continued clinical use of the Même prosthesis containing this particular type of foam appears questionable.

Biocompatible Materials↗