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Biomedical subjects

J Meredith

Publications and source records attributed to J Meredith.

At least 37 records · Page 2Linked to original sources
PubMed1992

Blunt cardiac injury.

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Abbreviated Injury Scale↗
PubMed1989

A cassette vector for the construction of antigen chimaeras of poliovirus.

A cassette vector has been constructed which allows the rapid and extensive modification of one of the neutralizing antigenic sites of the Sabin 1 poliovirus vaccine strain, P1/LSc 2ab. Unique restriction endonuclease sites flanking antigenic site 1 have been engineered into a full-length infectious Sabin 1 cDNA clone with minimal alteration to the coding sequence. This facilitates replacement of this region by oligonucleotides encoding foreign amino acid sequences. Our results indicate that this region is highly flexible in terms of the number and sequence of amino acids which can be accommodated.

Amino Acid Sequence↗
PubMed1988

Some major transport mechanisms of insect absorptive epithelia.

1. After hormonal stimulation, fluid reabsorption (JV) in locust hindgut from the KCl-rich, low-Na primary urine is driven primarily by an unusual mucosal electrogenic Cl- pump (JCl). 2. Cyclic-AMP increases JCl and also mucosal K+ and basolateral Cl- conductances, so that KCl absorption exceeds that of Na+ in rectum but not ileum. 3. Mucosal entry of Na+ occurs by exchange for NH4+ (H+), by cotransport with some neutral amino acids, and through putative channels. 4. However, transport of proline, the predominant organic substrate, is largely Na-independent and drives a sizable component of Jv in rectal but not ileal segments. 5. There is evidence for hormonal control of Na+ reabsorption in ileum but not rectum.

Absorption↗
PubMed1987

A grant rationing model for a health care system.

Most public health programs are created through a political process and the health administrator's resource allocation decision is influenced not only by the relative performance of the subunits but also by political considerations. This paper presents a goal programming model for rationing available grants to competing health care subunits on the basis of performance subject to resource and political constraints. Performance is defined in terms of output adjusted for non-compliance on the identified quality of care and administrative efficiency criteria. The quality and efficiency criteria are those specified by the Federal agency as amended by local funding authorities and subunit administrators through a Delphi process. The model has the advantage of flexibility and can be easily adapted to suit prevailing financial and political conditions. In particular, it can be used as a viable analytical tool in health care and other public service agencies where political considerations are important in resource allocation decisions.

Community Health Centers↗
PubMed1985

Increased tissue factor activity generation in vitro by canine blood leukocytes associated with allogeneic kidney transplantation and rejection.

Using a canine model, leukocyte populations enriched for monocytes and lymphocytes were isolated from blood during three week periods after kidney allotransplantation corresponding to episodes of acute rejection. Relative to controls, these cells incubated in vitro for five hours were found to generate increased amounts of PCA (procoagulant activity) characterized as tissue factor, the extrinsic clotting pathway activator. Controls included comparable blood leukocyte populations isolated from kidney autograft recipients and healthy animals. Differences in results for these two control groups were insignificant. These contrasts observed between allografted animals and controls demonstrate that leukocyte PCA generation is stimulated by the allogeneicity of histoincompatible kidneys rather than by direct effects of organ transplantation or non-specific postoperative effects. Results of in vitro transfer experiments provide evidence that cellular stimulation or induction in vivo accounted for the PCA increases observed. Stimulation of leukocyte tissue factor generation as a consequence of allogeneic kidney transplantation may in part account for coagulopathies and fibrin deposition during kidney rejection.

Animals↗
PubMed1984

Psychological factors in adjustment to orthognathic surgery.

The psychological adjustment of 30 orthognathic surgery patients was evaluated before and on three occasions after surgery. Results of preoperative testing showed the group to be well adjusted, and there were no major changes in psychological functioning as a result of surgery. Motivation for surgery included both functional and esthetic goals, and the majority of patients were satisfied with the results of surgery. The patient's perception of the surgeon was significantly related to pre- and postoperative adjustment. Two of the measures used, the Health Opinion Survey and the Impact Message Inventory, have potential as brief early screening devices to identify patients who may experience problems in psychological adjustment to orthognathic surgery.

Adolescent↗
PubMed1984

Excretion of ouabain by Malpighian tubules of Oncopeltus fasciatus.

An in vitro preparation of Malpighian tubules was used to investigate the excretion of the polar cardiac glycoside, ouabain, in Oncopeltus fasciatus. Tubules were found to consist of at least two morphologically and physiologically distinct segments, both of which metabolized ouabain. The distal segment (segment II) secreted primary urine and ouabain. Secretion of ouabain by segment II was not observed to occur against a concentration gradient and increased with increasing fluid secretion. The proximal segment (segment I) reabsorbed fluid and ouabain but not metabolites. Ouabain was reabsorbed against a strong concentration gradient (23-fold), was independent of fluid reabsorption, and increased with increasing fluid secretion by segment II. In rapidly secreting Malpighian tubules (a situation of high cardiac glycoside secretion by segment II), the presence of segment I reduced the excretion of ouabain by 84-93%, mainly by reducing ouabain concentration. It appears excretory loss of cardiac glycosides can be reduced in O fasciatus and thus may be a factor in the sequestration of cardiac glycosides in this insect.

Absorption↗
PubMed1984

Increased tissue factor activity of monocytes/macrophages isolated from canine renal allografts.

Kidney allografting was performed in a group of ten beagles, and viable leukocytes infiltrating the transplanted organs were isolated during episodes of acute rejection 5 or 6 days postoperatively. These infiltrate populations, consisting predominantly of lymphocytes and monocytes/macrophages, were found to have significantly increased amounts of procoagulant activity relative to control leukocytes isolated from circulating blood and lymph. Using nonspecific esterase staining in an agar microclot assay, procoagulant activity in the infiltrate leukocytes was found to reside in monocytes/macrophages rather than other coisolated cell types. By contrast, control monocytes from blood had no activity in this microclot assay. Procoagulant activity in the infiltrate cells was characterized as tissue factor. Increased amounts of this activator of the extrinsic pathway, as found in infiltrate monocytes/macrophages, may initiate clotting reactions and fibrin deposition within allografts.

Animals↗
PubMed1982

Effectiveness of high-frequency jet ventilation in management of an experimental bronchopleural fistula.

An animal model was prepared to compare the effectiveness of high-frequency jet ventilation (HFJV) with that of conventional intermittent positive pressure ventilation (IPPV) in managing bronchopleural fistula. In ten adult beagles, the left upper pulmonary lobe was resected and the left upper lobe bronchus was cannulated to establish a permanent bronchopleural fistula. Apposition of the middle lobe to the chest wall was examined via an open thoracotomy. Fistula leakage was measured with the thoracotomy closed, and chest tube drainage was set at 20 cm H2O. With HFJV, lung apposition was attained at lower peak (8.9 cm H2O) and expiratory (5.7 cm H2O) pressures than with IPPV (21.2 cm H2O Peak pressure and 10.7 cm H2O expiratory pressure). With equivalent arterial blood gases, fistula leakage was 47 per cent higher with IPPV than with HFJV (P less than .001). Each 5 cm of positive end expiratory pressure (PEEP) added increased fistula leakage similarly to both systems. Varying the frequency of HFJV did not alter leakage significantly, but increasing the driving pressure markedly increased leakage. Thus, experimentally, HFJV proved superior to IPPV in the management of bronchopleural fistula. When HFJV is used clinically to manage a bronchopleural fistula, the driving pressure should be kept as low as possible and PEEP should be limited. The ventilatory rate may be varied to achieve the desired PaCO2 without significantly affecting leakage through the fistula.

Animals↗
PubMed1982

Effect of anesthesia and splenectomy on antibody response to pneumococcal polysaccharide immunization.

Whether anesthesia-induced immunosuppression and postsplenectomy decreased antibody response are important in the timing of postsplenectomy pneumococcal vaccination was tested in 57 inbred 150 to 175 gm Fischer 344 rats immunized three weeks preoperatively (Group 1), immediately after anesthesia (Group II), and three weeks postoperatively (Group III). Groups IV and V were not immunized. All rats had splenectomy and one hour of 1 per cent halothane anesthesia. After intraperitoneal immunization of the rats with 5 mu g of Type III pneumococcal polysaccharide, weekly serum antibody levels were determined by radioimmunoassay. Six weeks postoperatively, Groups I through IV received an intravenous LD50 dose of Type III pneumococcus; Group V was challenged one week after operation. Survival was assessed every 12 hours for one week. Antibody responses among the groups were statistically equal, except on day 4 and day 26 postimmunization. On day 4, Group I had higher levels than Groups II and III (P less than .05), showing the spleen's role in early antibody production, and on day 26, Group I had much lower levels than Group II (P less than .05), indicating a short-term depressive effect of anesthesia and operation on ongoing antibody formation. Survival was equal among Groups I through IV. Survival in Group V was poorer than in Group IV (P less than 0.5), probably indicating that nonsplenic sites had acquired an enhanced ability to clear pneumococcus. The study shows, therefore, that anesthesia and splenectomy do not affect the timing of pneumococcal vaccination postsplenectomy.

Anesthesia, Inhalation↗
PubMed1981

Diagnosis and treatment of the hemiplegic patient with brachial plexus injury.

Brachial plexus injury was observed as a complication in 5 of 12 hemiplegic patients admitted over a 5-week period to an inpatient unit of the Rehabilitation Institute of Chicago. These patients exhibited unusual patterns of muscle atrophy and return of function in the impaired upper extremity. Occupational therapists may play an important part in the diagnosis and treatment of this complication of hemiplegia by promptly recognizing its subtle clinical signs and instituting appropriate therapy. Electromyography may be recommended to confirm this diagnosis. The treatment of choice is to maintain correct positioning of the limb both day and night, to use facilitation techniques for specific muscles in order to prevent atrophy, and to maintain passive range of motion as much as possible. Prevention of brachial plexus injury depends largely on the education of patient, family, and staff as to the potential hazards to a frail extremity that has no protective responses.

Aged↗