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Biomedical subjects

L F Martin

Publications and source records attributed to L F Martin.

At least 109 records · Page 6Linked to original sources
PubMed1981

A multiple-channel cochlear implant. Evaluation using speech tracking.

Two totally deaf patients who had received multiple-channel cochlear implants were tested using a speech "tracking" procedure in which they had to repeat verbatim passages of connected discourse. Their performance was assessed by calculating the tracking rate (words per minute) each session. Testing was carried out under two conditions--lipreading alone and lipreading in conjunction with a multiple-channel cochlear implant and laboratory speech processor. Lipreading with the cochlear implant increased the tracking rates by a factor of four for one patient and by a factor of two for the other when compared with lipreading alone.

Cochlear Implants↗
PubMed1981

The initial impact of a surgical AHES program on medical students' career decisions.

Since 1974 the University of Louisville has sent medical students to a rural area to receive their core surgical clerkship experience as part of an area health education system (AHES) program. This report reviews the first five years of the program and its effect on residency selection. Seventeen percent of the 679 students who graduated from the School of Medicine between 1976 and 1980 participated in this rural program. These students were similar to their urban university-based peers as a group in preclerkship evaluation criteria. Test scores on surgery examinations and examinations of the National Board of Medical Examiners did not differ between the two groups. Residency programs chosen by participants showed a similar distribution to those chosen by the university group, except in family practice. Twenty-six percent of the rural group chose family practice residencies, compared with 16 percent of the urban group. The early impact of the surgical AHES program is evaluated, and the need for continued follow-up is emphasized.

Career Choice↗
PubMed1981

A multiple-channel cochlear implant: an evaluation using open-set CID sentences.

A multiple-channel cochlear implant and speech processor have been used in two postlingually deaf adult patients with a total hearing loss, to enable them to perceive varying degrees of running speech. The results have veen confirmed with open-set CID everyday sentence tests. Using the implant alone, the patients obtained 8% and 14% scores with prerecorded material, and 34% and 36% scores for "live" presentations. This was equivalent to the perception of 35% of connected discourse. When the implant was used in conjuction with lipreading, improvements of 188% and 386% were obtained over lipreading alone, and the scores were 68% and 98% which were equivalent to the perception of 60% and 95% of connected discourse.

Adult↗
PubMed1980

Small bowel tumors: a continuing challenge.

Small bowel tumors are difficult to diagnose and are frequently not identified at initial evaluation. We retrospectively reviewed 25 consecutive cases to assess the efficacy of procedures currently used in diagnosis. Barium contrast studies were diagnostic in 14 (56%) of the cases. Enteroclysis provided one diagnosis after the initial barium study was negative. Of the 11 patients for whom barium studies were negative, angiography provided the diagnosis in six (three benign, three malignant). Endoscopy was never helpful. Laparotomy was required in five cases (three benign, two malignant) after repeated negative work-ups. An evaluation protocol which calls for each method as needed seems to provide the most reliable means of diagnosing small bowel tumors.

Adult↗
PubMed1980

Failure of gastric pH control by antacids or cimetidine in the critically ill: a valid sign of sepsis.

To compare the ability of antacids and cimetidine to control gastric pH and potential hemorrhage, 77 critically ill patients were randomized into two groups initially receiving either antacids (37 patients) or cimetidine (40 patients). Gastric pH was monitored hourly and the dosage of medication adjusted as required to maintain gastric pH above 4. Forty-nine patients maintained a pH above 4 while receiving a standard dose of antacids (29 patients) or cimetidine (20 patients). Only 8 of these 49 patients proved to be septic, compared to 20 of the 28 patients who required additional medication to maintain pH above 4 (P less than 0.001). There were five episodes of gastrointestinal hemorrhage occurring in septic patients who had a gastric pH consistently below 4 despite treatment. Excluding septic patients, 8 of 23 failed to maintain a gastric pH of 4 on cimetidine compared to 0 of 26 receiving antacids (P less than 0.005). The data suggest that (1) persistent failure of antacids and/or cimetidine to maintain gastric pH above 4 is yet another indicator of often unappreciated infection, (2) maintaining gastric pH above 4 largely prevents gastrointestinal hemorrhage, and (3) cimetidine is not as consistently effective as antacids in maintaining gastric pH above 4.

Adolescent↗
PubMed1979

Failure of cimetidine prophylaxis in the critically ill.

Stress ulcers with subsequent hemorrhage are a well-recognized cause of morbidity and mortality in patients hospitalized for other serious illnesses. In 39 critically ill patients, cimetidine was used as a prophylaxis against stress ulcers with the intent to keep the gastric pH level above 4. In 11 of the 39 patients, cimetidine alone did not effect consistent elevation of the gastric pH level above 4. Of the 11 patients, nine had positive blood cultures or clinical infection and five also developed renal failure. Five comatose patients never had pH greater than 4 on cimetidine alone. The mortality for those whose conditions failed to respond to cimetidine was five times greater than for those whose conditions responded to cimetidine. These data imply that a high-risk group of patients can be identified whose conditions may not respond to cimetidine treatment and whose gastric pH must be regularly monitored.

Acute Kidney Injury↗
PubMed1978

Lung mast cells and hypoxic pulmonary vasoconstriction in cats.

An attempt was made to reduce or eliminate lung mast cells in order to determine the involvement of mast cells in hypoxic pulmonary vasoconstriction. Anesthetized cats were exposed to acute hypoxia (10% O2) 20-24 h after no pretreatment, after total lung irradiation (3,000 r), after intravenous nitrogen mustard, or after combined lung irradiation and nitrogen mustard. None of the treatments reduced total or perivascular lung mast cell density, or reduced the pulmonary vasoconstrictor response to hypoxia. However, an inverse relationship between lung mast cell density and the pulmonary pressor response to hypoxia was observed. These results suggest that the presence of more lung mast cells may oppose hypoxic pulmonary vasoconstriction.

Animals↗
PubMed1974

A longitudinal study of blood pressure in childhood.

Blood pressures were taken in 609 children aged 6-18 in 163 families, 549 of whom had been studied 4 years earlier. Age and sex adjusted scores were expressed in standard deviation units (SDU). Analysis of variance again revealed the variance of blood pressures within families to be significantly less than among all children in this age group (p is less than 001. There was a significant positive relation between the follow-up and initial readings (regression coefficients: 0.24,p is less than .001 for systolic and 0.14,p = .001 for diastolic pressures). Of 88 children with initial systolic scores greater than 1 SDU above the mean, 65 percent had positive scores at follow-up, and 57 of 81 (70 percent) children with initial systolic scores less than 1 SDU below the mean had negative scores at follow up. These data suggest that stratification of blood pressures within peer groups begins and is detectable in childhood.

Adolescent↗
PubMedDate not supplied

Human DT-diaphorase, a potential cancer protecting enzyme. Its purification from abdominal adipose tissue.

The flavoprotein DT-diaphorase (EC 1.6.99.2) is believed to play an important role in the body's defense system. This enzyme has been purified 13,000-fold with a recovery of 58% from a cytosolic fraction of abdominal fat obtained from an obese patient undergoing elective surgery. Purification of the enzyme to electrophoretic homogeneity was achieved after two chromatographic steps: (1) affinity chromatography on azodicumarol Sepharose 6B; (2) anion exchange chromatography on DEAE Sephacel. The enzyme exhibits a monomer molecular mass of 32 kDa in SDS-PAGE and has 1 FAD prosthetic group per 32 kDa monomer. The FAD prosthetic group appears to be firmly attached to the apoproprotein. The enzyme reduces azodyes and quinones and demonstrates a broad substrate specificity. The enzyme has characteristics that are similar to DT-diaphorase purified from rodent liver, especially the rat liver enzyme. Estimated Km values for NADH, NADPH and menadione are 200, 140 and 3.3 microM, respectively. Vmax values for these substrates in the same order are 762, 667 and 294 mumol/mg.min. Dicumarol and warfarin exhibited competitive inhibition with pyridine nucleotides. The inhibition constants (Ki) for the drugs were estimated to be 10 nM and 2.2 microM, respectively. When compared to several other tissues, abdominal fat has one of the highest DT-diaphorase activities (Martin, L.F., Patrick, S.D. and Wallin, R. (1987) DT-diaphorase in morbidly obese patients. Cancer Lett., 36, 341-347), but the specific role of the enzyme in human fat is unknown.

Abdomen↗
PubMedDate not supplied

CT evaluation of posterior mediastinal teratoma.

Plain radiography and CT features of a posterior mediastinal teratoma are presented. Computed tomography confirmed the posterior mediastinal origin of this mass, added information about its content, and revealed apparent sparing of the surrounding structures, thus playing an important role in surgical planning.

Child, Preschool↗