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Biomedical subjects

C M Smith

Publications and source records attributed to C M Smith.

At least 127 records · Page 7Linked to original sources
PubMed1994

Bilirubin, ferritin, D-dimers and erythrophages in the cerebrospinal fluid of patients with suspected subarachnoid haemorrhage but negative computed tomography scans.

AIM: To assess the diagnostic value of cerebrospinal fluid (CSF) spectrophotometry, cytology, ferritin, and D-dimer measurements in the investigation of suspected subarachnoid haemorrhage in patients with negative or equivocal computed tomography (CT) scans. METHODS: CSF specimens submitted for assessment of xanthochromia were examined for erythrophages using a cytospin preparation stained with Wright's stain, for ferritin using the Ciba-Corning Magic IRMA assay, D-dimers using the Dimertest 2 latex agglutination slide test, and for bilirubin by scanning spectrophotometry. The patients were divided into three groups for data analysis and the results compared with the existing methods, CT, and angiogram results. Final diagnoses were reviewed by a consultant neurologist. RESULTS: Thirty six patients were recruited. In those patients with confirmed subarachnoid haemorrhage CSF cytology had a low sensitivity and there were false negative results with both the D-dimer and ferritin assays. Eleven patients with a negative or equivocal CT scan underwent angiography, but only one aneurysm and no arterio-venous malformations or bleeding points were identified. In the patient with the aneurysm there was no laboratory evidence of subarachnoid haemorrhage. Six patients had CSF abnormalities detected by the special tests only and in none of these cases was subarachnoid haemorrhage confirmed. All results were normal in four out of five cases of traumatic tap. CONCLUSIONS: This is a small study, but it shows that, depending on the timing of the lumbar puncture, false negative results can occur with both ferritin and D-dimer measurements. It suggests that neither of these tests adds significantly to the information provided by CT, visualisation of CSF, and spectrophotometry and confirms that, despite the use of spectrophotometry, D-dimer and ferritin assays in selecting patients for angiography, the proportion of patients with negative CT scans and colourless CSF with demonstrable vascular lesions remains low.

Bilirubin↗
PubMed1994

Sensory neuropathy in hereditary spastic paraplegia.

A large kinship is reported with dominantly inherited spastic paraplegia starting in the first decade of life; its clinical evolution was indistinguishable from that of "pure" hereditary spastic paraplegia (HSP). However, all patients studied had electrophysiological evidence of a predominantly sensory polyneuropathy, which was confirmed on nerve biopsy in three. The histological findings indicated virtually complete loss of large diameter fibres with relative preservation of small myelinated and non-myelinated fibres. The neuropathy was largely asymptomatic and there were no trophic ulcers. This family represents a distinct entity which differs from other reported cases of HSP with neuropathy by virtue of the clinical predominance of the pyramidal syndrome, the greater impairment of large fibre sensory modalities than of pain or temperature modalities, and the consequent absence of mutilation.

Adult↗
PubMed1994

Improvement in pulmonary hypertension and hypoxemia during nitric oxide inhalation in a patient with end-stage pulmonary fibrosis.

A patient with severe interstitial pulmonary fibrosis, hypoxemia, pulmonary hypertension, and cor pulmonale was given inhaled nitric oxide (NO) followed by intravenous PGE1 to assess the reversibility of pulmonary hypertension. During NO inhalation, there was marked reduction in pulmonary vascular resistance, increased cardiac output, and dramatic improvement in arterial oxygenation. There was no effect on systemic vascular resistance. In contrast, intravenous PGE1 led to rapid arterial oxygen desaturation and worsened dyspnea. The beneficial responses to inhaled NO in this patient suggest that, even in severe chronic lung disease, reversible pulmonary vasoconstriction is present. Inhaled NO thus has a potential therapeutic role as a selective pulmonary vasodilator in patients with interstitial pulmonary fibrosis and cor pulmonale.

Administration, Inhalation↗
PubMed1994

Reconstruction of images from radiofrequency electron paramagnetic resonance spectra.

This paper discusses methods for obtaining image reconstructions from electron paramagnetic resonance (EPR) spectra which constitute object projections. An automatic baselining technique is described which treats each spectrum consistently; rotating the non-horizontal baselines which are caused by stray magnetic effects onto the horizontal axis. The convolved backprojection method is described for both two- and three-dimensional reconstruction and the effect of cut-off frequency on the reconstruction is illustrated. A slower, indirect, iterative method, which does a non-linear fit to the projection data, is shown to give a far smoother reconstructed image when the method of maximum entropy is used to determine the value of the final residual sum of squares. Although this requires more computing time than the convolved backprojection method, it is more flexible and overcomes the problem of numerical instability encountered in deconvolution. Images from phantom samples in vitro are discussed. The spectral data for these have been accumulated quickly and have a low signal-to-noise ratio. The results show that as few as 16 spectra can still be processed to give an image. Artifacts in the image due to a small number of projections using the convolved backprojection reconstruction method can be removed by applying a threshold, i.e. only plotting contours higher than a given value. These artifacts are not present in an image which has been reconstructed by the maximum entropy technique. At present these techniques are being applied directly to in vivo studies.

Electron Spin Resonance Spectroscopy↗
PubMed1994

Referrals for inadequate progress of labour from the midwife obstetric units to the referral hospitals in Cape Town.

Referrals for inadequate progress of labour from the Midwife Obstetric Units (MOUs) to the referral hospitals are responsible for a significant part (approximately 5%) of the workload of these institutions in the Peninsula Maternal and Neonatal Service Region in Cape Town. It is essential for the maintenance of community credibility in the MOUs that patients who develop complications are timely and speedily transferred to the appropriate referral hospital. A sample of 251 patients, who were transferred from the MOUs to the referral hospitals for inadequate progress of labour in the first half of 1992, was analysed. The study showed that midwives in the MOUs had largely adhered to the Departmental referral criteria for that potentially serious complication of labour and had kept excellent records. The referrals, in terms of eventual outcome for the patients and their infants, had been largely appropriate. Several areas of concern were identified. These included incomplete assessment of the stage of labour on admission and inadequate monitoring of the fetal heart in a number of patients. Provision of analgesia in labour was generally inadequate. Ambulance delay was disturbingly common. Recommendations for measures to redress these management deficiencies are presented.

Female↗
PubMed1994

Hemorheologic alterations induced by incremental treadmill exercise in thoroughbreds.

Hemorheologic alterations induced by incremental treadmill exercise were examined in 5 Thoroughbreds. Blood viscosity; PCV; RBC filterability, density gradient profile, and shape; serum and RBC electrolyte concentrations; and plasma total solids and lactate concentrations were measured before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise. Exercise was associated with significant (P < 0.05) increases in PCV, blood viscosity, and plasma total solids concentration. After adjustment of PCV to 40% by adding or removing each horse's own plasma, blood viscosity remained significantly greater in the sample obtained at 13 m/s, compared with that in samples taken at rest. Filterability of RBC was significantly decreased at 13 m/s, compared with values from other sampling times. During exercise, a significantly greater proportion of the RBC were less dense and were found in the upper layers of the RBC density gradient profile, compared with resting values. This change was associated with a significant increase in RBC mean cell volume. Rapid increases in serum sodium and potassium concentrations during exercise were accompanied by significant increases in RBC potassium and chloride concentrations. This study revealed a consistent pattern of hemorheologic alterations associated with exercise in Thoroughbreds, suggesting that multiple hemorheologic tests are needed to adequately define these complex alterations during exercise in horses.

Animals↗
PubMed1994

Inherited glutathione-S-transferase deficiency is a risk factor for pulmonary asbestosis.

Pulmonary diseases attributable to asbestos exposure constitute a significant public health burden, yet few studies have investigated potential genetic determinants of susceptibility to asbestos-related diseases. The glutathione-S-transferases are a family of conjugating enzymes that both catalyze the detoxification of a variety of potentially cytotoxic electrophilic agents and act in the generation of sulfadipeptide leukotriene inflammatory mediators. The gene encoding glutathione-S-transferase class mu (GSTM-1) is polymorphic; approximately 50% of Caucasian individuals have a homozygous deletion of this gene and do not produce functional enzyme. Glutathione-S-transferase mu (GST-mu) deficiency has been previously reported to be associated with smoking-induced lung cancer. We conducted a cross-sectional study to examine the prevalence of the homozygous deletion for the GSTM-1 gene in members of the carpentry trade occupationally exposed to asbestos. Members of the United Brotherhood of Carpenters and Joiners of America attending their 1991 National Union conference were invited to participate. Each participant was offered a chest X-ray and was asked to complete a comprehensive questionnaire and have their blood drawn. All radiographs were assessed for the presence of pneumoconiosis in a blinded fashion by a National Institute for Occupational Safety and Health-certified International Labor Office "B" reader. Individual GSTM-1 status was determined using polymerase chain reaction methods. Six hundred fifty-eight workers were studied. Of these, 80 (12.2%) had X-ray abnormalities associated with asbestos exposure. Individuals genetically deficient in GST-mu were significantly more likely to have radiographic evidence of nonmalignant asbestos-related disease than those who were not deficient (chi 2 = 5.0; P < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Thrombolytic therapy for arterial occlusion: a mixed blessing.

Intra-arterial thrombolytic therapy is an important advance in the treatment of arterial occlusive disease. Reports of results, morbidity, and mortality have been highly variable. This review was undertaken to assess the recent results of thrombolytic therapy with urokinase (UK) at our institution. From 1988-1992, 42 lower extremities in 41 patients with severe peripheral vascular disease underwent intra-arterial thrombolytic therapy. Sites of occlusion consisted of 6 iliac, 21 superficial femoral, 11 popliteal, and 20 infra-popliteal segments. Lytic therapy consisted of a regional infusion of UK with concomitant heparin anticoagulation. The most common UK loading dose was 250,000 units (60,000-750,000) followed by a continuous infusion of approximately 100,000 units/hour (60,000-240,000) for up to 72 hours. Technical success, defined as partial or total resolution of the arterial occlusions, occurred in 26 (62%) limbs. A concomitant endovascular procedure was required in 19 extremities following successful lysis. Immediate clinical success, defined as restitution of a distal pulse or increase in ABI > 0.10, occurred in 22 of 26 technically successful procedures. The four clinical failures and all 16 technical failures required either a major amputation or revascularization. There were 18 major complications in 18 patients (43%): seven thromboembolic, two arterial dissections, nine hemorrhagic. Seven hemorrhagic complications required transfusion of 1-6 units of blood, and two deaths occurred due to postprocedural hemorrhage, shock, and myocardial infarction. Hemorrhage was not related either to the dose of UK or the duration of UK infusion. A combination of thrombolysis and endovascular intervention can be of significant benefit in selected patients with extremity ischemia. However, complications are frequent and may be lethal.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Effects of echinocytosis on hemorrheologic values and exercise performance in horses.

Effects of echinocytosis on blood rheology and exercise performance were evaluated for 5 Thoroughbreds. Echinocytosis was induced by administration of furosemide (1 mg/kg of body weight, IM, q 12 h) for 4 days. Furosemide treatment resulted in decreases in serum sodium and serum chloride concentrations and in RBC chloride and potassium concentrations. Echinocytosis was associated with increased RBC density as determined by RBC density gradient centrifugation. However, samples containing echinocytes were more filterable than control samples, indicating that echinocytes were not rigid cells. Erythrocyte sedimentation rate was decreased in blood samples containing echinocytes, indicating that cell-to-cell interaction was reduced. Whole blood viscosity was not altered by presence of echinocytes. Echinocytes did not impair the capacity of horses to complete treadmill exercise tests, nor did they alter heart rate or blood gas variables. However, plasma lactate concentration was higher in samples obtained during exercise at a treadmill speed of 9 m/s. Echinocytosis was associated with higher postrace creatine kinase activity. These data indicate that echinocytes may be dense, but not rigid cells, which have decreased tendency to aggregate and do not increase whole blood viscosity. Therefore, echinocytes are unlikely to inhibit or obstruct microvascular blood flow.

Animals↗
PubMed1994

Factors associated with appointment keeping in a family practice residency clinic.

BACKGROUND: Failure to keep an appointment not only affects the patient's health care, but also has an impact on the effectiveness and productivity of the medical facility. This study explored patient demographic factors associated with appointment keeping. METHODS: In a Midwestern, urban family practice residency clinic serving 2500 patient visits each month, data were obtained from the computer scheduling system and chart audits for 4669 patients who kept or missed 7283 physician appointments between April and June 1991. Independent variables studied were age, race and ethnicity, type of health insurance, marital status, sex, patient status, day and time of appointment, medical reason for the visit, and geographic proximity to the clinic. RESULTS: The kept-appointment rate for this study was 73.9%. Appointment keeping was associated with age, race and ethnicity, type of health insurance, the day of the appointment, the medical reason for the visit, and geographic proximity to the clinic. Rates of appointment keeping were higher for patients who were older, who were Asian or white, who had private or managed care insurance, who had longer distances to travel to the clinic, and those who had appointments scheduled for the day on which they contacted the clinic. CONCLUSIONS: Several identifiable factors significantly affect whether a patient will keep a clinic appointment. Our findings should be considered in program changes in appointment scheduling and follow-up methods for noncompliant patients.

Adolescent↗
PubMed1993

Potentiation of cyclosporine nephrotoxicity by nafcillin in lung transplant recipients.

The interaction between nafcillin and cyclosporine was examined in lung transplant recipients receiving cyclosporine-based immunosuppression. Nine recipients received nafcillin for one week posttransplant and 10 recipients did not receive nafcillin. Age, sex, pretransplant renal function, type of transplant procedure, use of cardiopulmonary bypass, and initial cyclosporine dose were not significantly different between groups. The degree of renal dysfunction during the early postoperative period was significantly greater in the lung recipients receiving nafcillin. Although cyclosporine doses were significantly higher in the nafcillin group, this was not reflected by differences in cyclosporine levels. No difference in survival or incidence of allograft rejection was seen--however, the incidence of viral infection was significantly higher in the patients who received nafcillin. Based on our findings the use of an alternative antibiotic for antistaphylococcal prophylaxis in transplant recipients receiving cyclosporine is recommended.

Adolescent↗
PubMed1993

Primary diagnosis predicts prognosis of lung transplant candidates.

Optimal timing for consideration of lung transplantation remains unknown. This study examined survival in patients with end-stage lung disease awaiting transplantation. Primary disease group and relevant indicators were evaluated. Ninety-three patients who met selection criteria for lung transplantation were included in this retrospective review. Of this total, 31% underwent transplantation, 38% remain waiting, and 31% died. Results demonstrate that the six-month actuarial survival rate was 89% for Eisenmenger's syndrome, 81% for emphysema, 74% for cystic fibrosis, 60% for primary pulmonary hypertension, and 38% for interstitial lung disease. Parameters found to be significant included a higher mean right atrial pressure in primary pulmonary hypertension patients who died awaiting transplantation, and lower forced expiratory volume in one second and forced vital capacity measurements in cystic fibrosis patients who died awaiting transplantation. We conclude that primary disease significantly affects survival in candidates awaiting transplantation. Reliable indicators predictive of survival are not available. Earlier referral for consideration of lung transplantation is recommended.

Adolescent↗
PubMed1993

Reliability of the Self-Administered Alcoholism Screening Test (SAAST) in psychiatric inpatients.

Identification of alcohol abuse in psychiatric patients is essential, since it can confuse the clinical picture and complicate treatment. The utility and reproducibility of the Self-Administered Alcoholism Screening Test (SAAST) was assessed in 236 acutely ill psychiatric patients. Both an initial SAAST given at admission, and a second SAAST given shortly before discharge, were completed by 173 (73%) patients; significant correlation (r = 0.85) was found between scores on SAAST 1 and SAAST 2. Only 41 (17%) patients were unable or refused to complete the initial SAAST and the majority of these received a schizophrenia diagnosis. SAAST scores were also significantly correlated with the clinical assessments and histories. Most (76%) patients with a current or past history of alcohol abuse scored in the "alcoholic" (> or = 8) range on one or both SAASTs. Men were almost twice as likely as women to have a history of alcohol abuse, and significantly more likely to score > or = 8 on the SAAST. The SAAST could be completed by the majority of acutely ill psychiatric patients even at admission, and was clinically useful in the diagnosis of alcohol abuse, especially when used in conjunction with the clinical interview.

Adolescent↗
PubMed1993

Influence of heat on platelet biochemistry, structure, and function.

The present investigation has evaluated the influence of temperatures ranging from 37 degrees C to 45 degrees C for intervals of 30, 60, and 90 minutes on the biochemistry, morphology, and function of human platelets. Exposure to temperatures up to 43 degrees C for an hour did not significantly alter platelet morphology or physiologic response to aggregating agents. Samples of platelets heated at 43 degrees for 60 minutes lost their ability to aggregate in response to arachidonate, but sensitivity was restored by pretreatment with epinephrine. Platelets heated to 45 degrees C for 90 minutes were converted from discs to spheres and failed to aggregate in response to all agonists, whether or not they were pretreated with epinephrine. The platelets heated at 45 degrees C for 90 minutes could adhere to formvar or denuded subendothelium but were unable to extend pseudopods or to spread. They maintained normal levels of adenine nucleotides and serotonin but failed to secrete these products on stimulation. Studies with fibrinogen coupled to gold (Fgn/Au) revealed only a few particles bound to glycoprotein IIb-IIIa (GPIIb-IIIa) on platelets heated at 43 degrees C for 90 minutes. Ligands that did bind to GPIIb-IIIa were transported to the open canalicular system. Biochemical studies demonstrated normal synthesis of thromboxane B2 and calcium flux by platelets heated at 45 degrees C for 90 minutes. Polyacrylamide gels of platelets heated at 45 degrees C for 90 minutes showed an increase in talin incorporation into heated platelet cytoskeletons but no increase in filamentous actin. The findings indicate that impaired function of heated platelets is due to the influence of heat on cytoskeletal proteins important for pseudopod extension, shape change, expression of GPIIb-IIIa, or other surface membrane receptors and secretion, but that impaired function is not due to inhibition of biochemical systems involved in activation events.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1993

Pharmacokinetic model for predicting sulfamethazine disposition in pigs.

Concentration of sulfamethazine was measured in plasma and tissues (fat, liver, kidney, spleen, lungs, and skeletal muscle) of pigs given the drug IV and PO. The plasma concentration vs time curve was best described by a 2-compartment model, with a distribution half-life of 0.46 hour and an elimination half-life of 16.9 hours. Bioavailability after oral administration was 85.8 +/- 5.3%. The tissue and plasma sulfamethazine concentration vs time data were used to develop a multi-compartment pharmacokinetic model of sulfamethazine disposition in pigs. Plasma and tissue concentrations of sulfamethazine in pigs were measured at various intervals after multiple oral doses of sulfamethazine, and were compared to concentrations predicted by the model. Model predictions for tissue concentrations of sulfamethazine after addition of the drug to feed (110 micrograms/g of feed for 98 days; 550 micrograms/g for 30 days) were compared to results from other studies. The model accurately predicted the number of days for sulfamethazine concentration to fall below 0.1 micrograms of tissue/g (0.1 ppm, the tolerated concentration) in various tissues.

Administration, Oral↗
PubMed1993

Circulatory and respiratory responses of spontaneously breathing, laterally recumbent horses to 12 hours of halothane anesthesia.

Cardiovascular and respiratory changes that accompany markedly long periods (12 hours) of halothane anesthesia were characterized. Eight spontaneously breathing horses were studied while they were positioned in left lateral recumbency and anesthetized only with halothane in oxygen maintained at a constant end-tidal concentration of 1.06% (equivalent to 1.2 times the minimal alveolar concentration for horses). Results of circulatory and respiratory measurements during the first 5 hours of constant conditions were similar to those previously reported from this laboratory (ie, a time-related significant increase in systemic arterial blood pressure, cardiac output, stroke volume, left ventricular work, PCV, plasma total solids concentration, and little change in respiratory system function). Beyond 5 hours of anesthesia, arterial blood pressure did not further increase, but remained above baseline. Cardiac output continued to increase, because heart rate significantly (P < 0.05) increased. Peak inspiratory gas flow increased significantly (P < 0.05) in later stages of anesthesia. There was a significant decrease in inspiratory time beginning at 4 hours. Although PaO2 and PaCO2 did not significantly change during the 12 hours of study, PVO2 increased significantly (P < 0.05) and progressively with time, beginning 6 hours after the beginning of constant conditions. Metabolic acidosis increased with time (significantly [P < 0.05] starting at 9 hours), despite supplemental IV administered NaHCO3. Plasma concentrations of eicosanoids: 6-keto-prostaglandin F1 alpha (PGF1 alpha, a stable metabolite of PGI2), PGF2 alpha, PGE, and thromboxane (TxB2, a stable metabolite of TxA2) were measured in 5 of the 8 horses before and during anesthesia. Significant changes from preanesthetic values were not detected. Dynamic thoracic wall and lung compliances decreased with time.

Anesthesia, Inhalation↗
PubMed1992

Detergent-resistant cytoskeleton of the surface-activated platelet differs from the suspension-activated platelet cytoskeleton.

This study contrasts the protein composition of the detergent-resistant cytoskeleton of platelets fully spread on glass with the cytoskeletal composition of resting platelets and platelets aggregated in suspension with thrombin. Complete Triton X-100-insoluble cytoskeletons were isolated from spread, resting, and suspension-activated platelets in the presence of protease inhibitors, solubilized in sodium dodecyl sulfate/EDTA and analyzed on reduced, one-dimensional polyacrylamide gels. The protein composition of the cytoskeletons differed both qualitatively and quantitatively. Most notable were more extensive incorporation of total protein, talin, and vinculin into the cytoskeleton of spread platelets than the cytoskeleton of suspension-activated platelets. Varying the concentration and time of exposure to thrombin during suspension activation did not mimic the cytoskeletal changes of surface activation. Scanning electron microscopy, measurement of lipid phosphorus content, and varying the duration of Triton extraction did not show incomplete solubilization or nonspecific trapping of constituents in the spread platelet cytoskeleton. Proteolysis of talin was minimal in suspension-activated platelets and in platelets spread for 50 minutes. The differences in the detergent-resistant cytoskeletons of surface- and suspension-activated platelets indicate significant divergence in the physiologies of platelet spreading on surfaces and platelet activation in suspension.

Adult↗