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Biomedical subjects

C R Smith

Publications and source records attributed to C R Smith.

At least 289 records · Page 16Linked to original sources
PubMed1984

Taurocholate accelerates bile canalicular contractions in isolated rat hepatocytes.

The influence of sodium taurocholate on bile canalicular contractions was examined by time-lapse cinephotomicrography of isolated rat hepatocytes in primary monolayer cultures. Frame-by-frame analyses indicates that as the dose of taurocholate increased, the number of contractions increased in a dose-dependent manner up to 5 microM. Because bile canaliculi are the smallest biliary passages across which bile secretion occurs, and because it is known that taurocholic acid within the dose range used in these studies causes a linear increase in bile secretion, the results suggest that canalicular contractions may be a function of canalicular bile secretion.

Animals↗
PubMed1984

Modeling HTL of industrial workers using multiple regression and path analytic techniques.

This study compared path analytic with multiple regression analyses of hearing threshold levels (HTLs) on 258 adult textile workers evenly divided into low- and high-noise exposure groups. Demographic variables common in HTL studies were examined, with the addition of iris color, as well as selected two-way interactions. Variables of interest were similarly distributed in both groups. The results indicated that (1) different statistical procedures can lead to different conclusions even with the same HTL data for the same Ss; (2) conflicting conclusions may be artifacts of the analytic methodologies employed for data analysis; (3) a well-formulated theory under which path analytic techniques are employed may clarify somewhat the way a variable affects HTL values through its correlational connections with other antecedent variables included in the theoretical model; (4) multicollinearity among independent variables on which HTL is regressed usually presents a problem in unraveling exactly how each variable influences noise-induced hearing loss; and (5) because of the contradictory nature of its direct and indirect effects on HTL, iris color provides little, if any, explanatory assistance for modeling HTL.

Adult↗
PubMed1984

Recognition of dementia among medical patients.

To determine how accurately dementia was diagnosed among medical inpatients, we compared the judgments of medical interns with diagnoses based on standard criteria. Fifty-seven interns rendered opinions regarding the presence of dementia in 380 medical inpatients who were simultaneously examined by physician-investigators applying criteria derived from DSM III. The sensitivity and specificity of diagnosis by interns were 79% and 80%, respectively. Patients who were misdiagnosed as demented were less likely to be high school graduates than their correctly classified nondemented counterparts, and those with unrecognized dementia were more likely to be younger than 65 years than patients whose dementia was recognized by house staff. It is concluded that misdiagnosis is related to age and educational status and that attention to these factors may improve diagnostic accuracy.

Adult↗
PubMed1984

Effect of morphine sulfate concentration on flow rate in an implantable reservoir pump.

The effect of morphine sulfate concentration on flow rate in an implantable pump was studied. Solutions containing morphine sulfate 5 mg/3 ml, 10 mg/3 ml, 20 mg/3 ml, and 200 mg/3 ml were prepared from morphine sulfate powder; a solution containing morphine sulfate 20 mg/3 ml with bupivacaine hydrochloride 0.125% was also prepared. Sterile water was used for preparing the morphine solutions and as the control solution. A model 400 Infusaid pump was filled with 50 ml of the drug solution, placed in a water bath at 37 degrees C, and allowed to equilibrate for three hours. Samples of each concentration of morphine solution and control solution were then collected in an analytical graduate over 20-hour periods. Between each collection period, the pump was flushed twice with sterile water. Five samples of each morphine solution and control solution were collected. The osmolality of one sample of each solution was determined to assess drug concentration indirectly; morphine sulfate concentrations were not actually measured. Actual solution volumes collected during the 20-hour collection periods were corrected to 24 hours to allow comparison with the pump's preset daily flow rate. Collection volumes and calculated daily flow rates decreased with increasing morphine sulfate concentrations and solution osmolalities; a significant positive correlation between osmolality and assumed drug concentration was found. The flow rate of the solution containing morphine 200 mg/3 ml was approximately equal to the pump's stated flow rate; flow rates for all other solutions were higher than the stated flow rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Infusions, Parenteral↗
PubMed1983

Immunohistochemical and electron microscopic assessment of childhood rhabdomyosarcoma. Increased frequency of diagnosis over routine histologic methods.

Histologic examination was carried out in 65 cases of childhood rhabdomyosarcoma (RMS), 53 embryonal, and 12 alveolar. Cross-striations were seen on light microscopy in 12 (23%) embryonal and 4 (33%) alveolar tumors. The capacity of immunohistochemical staining (PAP technique) to increase diagnostic accuracy was assessed, using antibodies against myoglobin, the MM isoenzyme of creatine kinase, desmin, calcium magnesium-dependent ATPase of sarcoplasmic reticulum and calsequestrin. Myoglobin was detected in 16 (30%) embryonal and eight (67%) alveolar RMS, higher numbers than obtained by viewing cross-striations on light microscopy. The creatine kinase antibody was slightly better than the antibody to myoglobin and 15 of 25 (60%) embryonal RMS were positive when both specificities were used. The remaining three antibodies were less useful. Of 13 (two alveolar and 11 embryonal) RMS studied by electron microscopy, four showed cross-striations, contained late myoblasts, and were positive for myoglobin. Three additional cases showed only late myoblasts and one of these was positive for myoglobin. Thus, 16 of 25 (64%) of the embryonal and seven of nine (78%) of the alveolar RMS showed either positive immunostaining or ultrastructural features of RMS. This study indicates that a combination of immunohistochemical staining, using antimyoglobin and anticreatine kinase (MM isoenzyme) antibodies, and electron microscopy are useful markers in the diagnosis of childhood RMS.

Ca(2+) Mg(2+)-ATPase↗
PubMed1983

Netilmicin and gentamicin multidose kinetics in normal subjects.

Multidose netilmicin and gentamicin kinetics were studied in 20 healthy subjects who received 1.7 mg/kg gentamicin (n = 10) or netilmicin (n = 10) as a 20-min infusion every 8 hr for 10 days (28 doses) during a randomized, double-blind comparative trial designed to study adverse effects and kinetics of netilmicin and gentamicin. Multidose kinetics were of the same order for gentamicin and netilmicin with the exception of the terminal plasma t 1/2 (94 and 156 hr) and the volume of distribution at steady state (450 and 1072 ml/kg). Mean peak plasma concentrations of netilmicin were slightly lower than gentamicin. Percentage of the dose eliminated in urine did not differ for the two aminoglycosides. Aminoglycoside was detectable in plasma and continued to be eliminated in urine for at least 6 days after the final dose. The plasma concentration-time profiles for both netilmicin and gentamicin were well fitted with the sum of three exponential terms; urinary excretion rates-time plots showed biexponential decay. None of the subjects had any auditory, vestibular, or renal toxicity. Although the data confirm a deep tissue compartment, they suggest that the kinetic processes involved may be more complex than previously supposed.

Adult↗
PubMed1983

Influence of a "discharge interview" on patient knowledge, compliance, and functional status after hospitalization.

Physicians commonly assume that they can educate hospitalized patients to follow prescribed treatment plans after discharge. In a prospective, controlled study, we assessed the effectiveness of a discharge interview given to each of 545 hospitalized patients assigned to one of four groups: a group in which the physicians caring for the patients received a 35-minute tutorial on how to conduct a discharge interview (n = 181), a group that received a 15-minute discharge interview from an investigator (n = 53), a group that received both interventions (n = 63), or a control group (n = 248). One month after discharge, all patients were telephoned, and a standardized questionnaire was administered. Results revealed that, 1 month after discharge, there were no significant differences among the four groups in knowledge of diagnosis, symptom status, activity level, medication knowledge and compliance, appointment keeping, and rates of rehospitalization. These results suggest that effective inpatient education may require more than a discharge interview.

Evaluation Studies as Topic↗
PubMed1983

Effect of furosemide on aminoglycoside-induced nephrotoxicity and auditory toxicity in humans.

We analyzed data from three prospective, controlled, randomized, double-blind clinical trails to determine whether furosemide increases the nephrotoxicity and auditory toxicity of aminoglycosides. All patients who received at least 72 h of treatment and who had no other cause for nephrotoxicity or auditory toxicity were included in the analysis. Nephrotoxicity developed in 10 of 50 (20.0%) patients given furosemide and in 38 of 222 (17.1%) patients not given furosemide (P greater than 0.3). Auditory toxicity developed in 5 of 23 patients (21.7%) given furosemide and in 28 of 119 patients (23.5%) not given furosemide (P greater than 0.3). In each case, the groups receiving and not receiving furosemide did not differ in mean age, initial creatinine, duration of aminoglycoside therapy, mean change in auditory acuity or creatinine, mean number of days to the development of toxicity, the frequency with which gentamicin, tobramycin, amikacin, or cephalothin was administered, or the mean predose and 1-h postdose plasma aminoglycoside levels. We conclude that furosemide use should not be considered a major risk factor for the development of aminoglycoside-induced nephrotoxicity or auditory toxicity.

Aminoglycosides↗
PubMed1983

Five-year blood pressure control and mortality following health education for hypertensive patients.

Three health education interventions for urban poor hypertensive patients were introduced sequentially in a randomized factorial design: 1) an exit interview to increase understanding of and compliance with the prescribed regimen; 2) a home visit to encourage a family member to provide support for the patient's regimen; and 3) invitations to small group sessions to increase the patient's confidence and ability to manage his/her problem. Previous evaluation of the initial two-year experience demonstrated a positive effect of the educational program on compliance with the medical treatment and blood pressure control. Data accumulated over an additional three years, including mortality analysis, are now presented. The study group consisted of the same cohort of 400 ambulatory hypertensive outpatients in the eight experimental and control groups. The five-year analysis shows a continuing positive effect on appointment keeping, weight control, and blood pressure control. All-cause life table mortality rate was 57.3 per cent less for the experimental group compared to the control group (12.9/100 vs 30.2/100, p less than .05), while the hypertension-related mortality rate was 53.2 per cent less (8.9/100 vs 19.0/100, p less than .01). The results from this longitudinal study provide evidence to encourage health practitioners to utilize such educational programs in the long-term management and control of high blood pressure.

Behavior↗
PubMed1983

Phalloidin alters bile canalicular contractility in primary monolayer cultures of rat liver.

We observed the motility of bile canaliculi in isolated rat hepatocytes obtained from animals that were pretreated with phalloidin (500 micrograms/kg body wt) for 1 and 3 days. Time-lapse cinephotomicrographs were taken in each experiment and in controls for 16.25 h. As we previously reported in normal hepatocytes, active contractions of bile canaliculi were observed. The number of contractions was 127.6 in controls, compared with 58.0 in 1-day phalloidin pretreated and 16.2 in 3-day phalloidin pretreated groups. The contraction process itself was not normal in the experimental groups, the contraction phase being slow and sustained. The altered canalicular motility depended on the dose of phalloidin administered. These results suggest that the integrity of actin filaments is necessary for normal bile canalicular motility. Further, dysfunction of actin microfilaments with altered canalicular motility may be involved in the pathogenesis of canalicular cholestasis.

Animals↗
PubMed1983

Amylase:creatinine clearance ratios, serum amylase, and lipase after operations with cardiopulmonary bypass.

Forty-two adults who underwent cardiac operations were studied prospectively for evidence of clinical or subclinical pancreatitis. Clinically detectable pancreatitis was not seen. Serum amylase and lipase levels did not change significantly following operation. The amylase:creatinine clearance ratio (ACCR) immediately following operation was abnormally elevated in 31% of the samples obtained, and the mean ACCR increased from 2.08 +/- 1.85% before operation to 6.2% +/- 6.77% (P less than 0.05). An abnormally elevated ACCR was most often associated with a low urine creatinine concentration. The mean urine creatinine level decreased significantly from 78 +/- 53 mg/dl before operation to 38 +/- 49 mg/dl immediately following operation (P less than 0.02), and 73% of the samples obtained at that time had an abnormally low urine creatinine level (P less than 0.01). The abnormalities observed in ACCR and urine creatinine could not be related to any of several variables presumed to reflect the degree of perioperative physiologic stress, nor could they be related to postoperative hemodynamic performance. It was concluded that ACCR rises following cardiac operation because of perioperative changes in renal function, and not as a reflection of subclinical pancreatic injury.

Adult↗
PubMed1983

Intrahepatic cholestasis as a canalicular motility disorder. Evidence using cytochalasin.

A rich network of actin-containing microfilaments are associated with the plasma membrane of the liver cells. These filaments are especially numerous in the pericanalicular region. Recently, active contractions of bile canaliculi have been observed in normal coupled isolated hepatocytes. In this report, we document that this motility behavior is abolished by cytochalasins B and D. Other cytoplasmic contractile movements are also reduced or lost after a brief initial period of enhanced surface activity with the formation of zeiotic blebs. The lack of contractile activity of bile canaliculi is accompanied by the gradual dilation of canalicular lumina. Since there is overwhelming evidence that the functional effects of the cytochalasins on cell motility are due to their effects on actin filaments, we propose that the altered canalicular contractility observed is due to the effects of cytochalasin on pericanalicular actin filaments. If bile canalicular contractility is a requirement for normal bile flow, then interference with this mechanism may be a factor in the pathogenesis of some types of intrahepatic cholestasis.

Animals↗