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Biomedical subjects

J L Clark

Publications and source records attributed to J L Clark.

At least 37 records · Page 2Linked to original sources
PubMed1994

Retrospective assessment of solvent exposure in paint manufacturing.

This paper describes how exposure to solvents at two large paint making sites was assessed in a study carried out to investigate the possibility of neuropsychological effects resulting from long term exposure to organic solvents. A job exposure matrix was constructed by buildings and year. A detailed plant history was taken and this was used to identify uniform exposure periods during which workers' exposure to solvents was not thought to have changed significantly. Exposure monitoring data, collected by the company before the study, was then used to characterise exposure within each uniform exposure period. Estimates were made for periods during which no air monitoring was available. Individual detailed job histories were collected for subjects and controls. The job histories were used to estimate exposure on an individual basis with the job exposure matrix. Exposure was expressed as duration, cumulative dose, and intensity of exposure. Classification of exposure by duration alone was found to result in misclassification of subjects.

Environmental Monitoring↗
PubMed1994

Management of common anxiety disorders.

Anxiety disorders affect 16 percent of the U.S. population. Family physicians treat 90 percent of patients presenting with one or more anxiety disorders. Common anxiety disorders include generalized anxiety disorder, panic disorder and social phobia. Differentiation among these disorders may be difficult, since symptoms and presentations are often similar. Underlying medical disorders and depressive illness may mimic or coexist with anxiety disorders. The chronic, remitting and relapsing nature of anxiety disorders requires the institution of a long-term plan of care. The integration of pharmacologic and psychotherapeutic interventions generally produces the greatest benefit to patients. Pharmacotherapeutic options frequently prescribed by family physicians include benzodiazepines, beta blockers, monoamine oxidase inhibitors, tricyclic antidepressants and azapirones. Useful psychotherapeutic models featuring brief interventions include supportive and cognitive approaches, and behavioral therapies, such as biofeedback, in vivo exposure and systematic desensitization.

Anti-Anxiety Agents↗
PubMed1993

The personality typology of black college students: evidence for a characteristic cognitive style?

This study examined the distributions across personality types (as assessed by the Myers-Briggs Type Indicator) of two samples of black college students (ns = 315 and 447) in comparison to norming data from two manuals. Major differences were found between the black and white samples with regard to the proportions classified as Extroversion-Intuition-Feeling-Perception (ENFP) and Introversion-Sensing-Thinking-Judging (ISTJ). Much higher proportions of the black samples were also clustered at the sensing pole of the perceptual dimension. The findings are discussed in terms of their implications for the existence of a unique black "cognitive style."

Adult↗
PubMed1991

Laser midline glossectomy as a treatment for obstructive sleep apnea.

Multiple site specific procedures have been proposed to treat obstructive sleep apnea syndrome (OSAS). Midline glossectomy (MLG) is a procedure that directly enlarges the hypopharyngeal airspace using the carbon dioxide laser. The initial experience of 12 patients is presented. Midline glossectomy as the sole procedure was performed on 11 patients who had failed uvulopalatopharyngoplasty (UPPP) and who were felt to have significant hypopharyngeal collapse on physical examination and Müller's maneuver. One patient with primary hypopharyngeal narrowing underwent MLG. Five (42%) were considered responders with Respiratory Disturbance Index (RDI) decreasing from 60.6 per hour to 14.5 per hour. In seven nonresponders, there was no significant change in the RDI (62.6 events per hour to 48.4 events per hour). Cephalometric analysis showed that responders tended to be more retrognathic (sella-nasion-supramentale (S-N-B = 74.4 degrees)) than nonresponders (S-N-B = 79.3 degrees). Responders were significantly less obese (body mass index (BMI = 30.6)) than nonresponders (BMI = 37.9). There were five minor complications including minor bleeding (n = 3), prolonged odynophagia (n = 1), and minor change in taste (n = 1). There were no major complications, and no persistent difficulties with speech or swallowing. These results demonstrate that direct surgical modification of the tongue base and associated structures can significantly impact obstructive apnea. Midline glossectomy or similar procedures may be useful in a subset of patients with OSAS.

Follow-Up Studies↗
PubMed1991

Impact of splenectomy on survival following gastrectomy for adenocarcinoma.

From 1972 to 1985, 161 palliative and 99 curative gastrectomies were performed, including splenectomy (SPL), in 49 and 42 patients, respectively. The relative contribution of tumor histology and location of primary tumor within the stomach to median survival times in months (MST) was examined by chi-square analysis for patients who had SPL and those who did not. MST for the 40 patients treated by curative gastrectomy and SPL was 33 months compared with 43.5 months in the 56 patients treated by curative gastrectomy without SPL (P = .24). Three postoperative deaths were excluded from this analysis. Neither tumor location nor the histological type had a statistically significant impact on MST within these two groups. SPL was not found to have statistically significant impact on survival following curative gastrectomy. In 46 patients treated by palliative gastrectomy with SPL the MST was 10.5 months compared with 15.5 months in 110 patients who were treated by palliative gastrectomy without SPL (P = .007). Five postoperative deaths and three patients in which primary tumor location could not be accurately determined were excluded from this analysis. The MST of 23 patients treated by SPL who had poor or undifferentiated histology was 8 months, compared with 15 months in 73 patients with similar histology not treated by SPL (P = .02). There was no statistically significant difference in MST between palliative gastrectomy patients who had well or moderately differentiated histology treated with (n = 23) and without (n = 37) SPL (P = .11). The impact of SPL on MST following palliative gastrectomy was not significantly influenced by tumor location in the stomach.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1990

Widespread silent transmission of pertussis in families: antibody correlates of infection and symptomatology.

Four children with pertussis and their 18 family members were subjects of a 1-year study to detect infection and antibody responses to Bordetella pertussis. Attack rate for pertussis infection in contacts was 83%. Two-thirds of cases in these immunized contacts were subclinical. All infected family contacts had diagnostically elevated serologic tests for pertussis at the time the index case was diagnosed. Culture identified only 20% of infected contacts. Infected individuals had a mean of 5.5 of 10 antibody tests diagnostic for recent infection. ELISA assay for IgG to pertussis toxin and assay for IgA to filamentous hemagglutinin on serum and nasal secretions were the most discriminating diagnostic tests. Index cases and immunized contacts had different type and timing of antibody responses, making a single assay or sampling unable to identify all infected individuals. Symptomatic infection was characterized by higher magnitude of pertussis toxin antibody response and asymptomatic infection by filamentous hemagglutinin. After pertussis immunization, immunity to disease is greater than is protection from infection.

Antibodies, Bacterial↗
PubMed1990

Serologic evidence of subclinical pertussis in immunized children.

Incidental to a vaccine study involving 783 immunized children conducted at two study sites, inner city children had significantly higher geometric mean pertussis agglutinin titers compared with suburban children just before the fourth dose of diphtheria-tetanus-whole cell pertussis vaccine (47 vs. 25; P less than 0.001). Higher titers in the inner city were correlated with residence in census tracts where cases of pertussis were reported. Three hundred thirty-two children in a placebo arm of the study who were clinically observed and had paired serum samples taken during a 2- to 4-month period were analyzed for evidence of natural Bordetella infection. Twelve (11%) inner city children and three (1.3%) suburban children had spontaneous 4-fold or greater rises in at least two different pertussis antibodies measured (agglutinin, antitoxin or enzyme-linked immunosorbent assay for IgG to pertussis toxin, IgG and IgA to filamentous hemagglutinin). Eighty percent of these children had IgA to filamentous hemagglutinin. Nine of 12 inner city children with serologic evidence of pertussis lived within 6 blocks of a case of pertussis reported within 1 month of the observed antibody rise in study subjects; none had a household member with pertussis and none had symptomatic disease.

Agglutination Tests↗
PubMed1990

Olfactory neuroblastoma: clinicopathologic and immunohistochemical characterization of four representative cases.

Olfactory neuroblastomas are rare tumors whose clinical prognosis is not predictable by assessment of initial stage or grade. The pathologic diagnosis is often difficult because of the wide range of the patient's age and histologies. In this report, we document that the diagnosis of olfactory neuroblastoma can be clarified by immunohistochemical demonstration of a unique antigenic profile that can be obtained in routinely processed biopsies. We describe four cases of olfactory neuroblastoma diagnosed and treated from 1979 to 1989, each confirmed by immunohistology. One of our patients was misdiagnosed twice at an outside institution, first as having nasopharyngeal carcinoma and then as having small-cell, undifferentiated "oat cell" carcinoma. Despite accurate tumor diagnosis and appropriate therapy, we found that there was no apparent correlation of clinical outcome with Kadish clinical stage or histologic grade of tumor.

Adult↗
PubMed1990

Metastatic carcinoma of the jaws: report of a case.

Primary malignant tumors of the mouth and jaws usually do not present a diagnostic challenge to oral surgeons or otolaryngologists. However, recognition of metastatic tumors in the mouth and jaws is much more difficult. A case is presented of metastatic carcinoma from the lung to the soft tissue of the oral cavity. Histopathology of the lesions in the lung and oral cavity as well as the chest x-ray and the Panorex x-ray are presented. The patient refused palliative treatment, became malnourished, and died. A review of the pertinent literature is also presented.

Aged↗
PubMed1990

Adjuvant 5-FU and MeCCNU improves survival following curative gastrectomy for adenocarcinoma.

During the 13-year period ending December 31, 1984, 51 patients treated by curative gastrectomy for gastric adenocarcinoma invasive beyond the submucosa were eligible to enter adjuvant chemotherapy trials. Twenty-one of 22 patients in the first treatment group (FMe) received 5-fluorouracil and a nitrosourea. The second group of eight patients received the same drugs plus Adriamycin (FAMe). Twenty-one patients were observed as surgical controls. Each adjuvant treatment group was subdivided into groups of patients with zero to four or five or more lymph node metastases for survival analysis. Fifteen patients were alive without evidence of disease at five years. Analysis of variance of survival times showed that lymph node status (P = 0.0001) and adjuvant chemotherapy (P = 0.01) were statistically significant prognostic variables. The FMe group had the best survival. A Fisher's exact test showed that the FMe group had a greater proportion of five-year survivors (P = 0.0217) than the no treatment arm. Patients with only zero to four positive lymph nodes in the FMe group had a statistically greater number of five-year survivors than patients in the no treatment arm (P = 0.0155). In this series, postoperative 5-fluorouracil and MeCCNU significantly improved the survival times of patients after curative gastrectomy for adenocarcinoma as compared with surgical controls.

Adenocarcinoma↗
PubMed1989

Endoscopic ablation of esophageal malignancies with the neodymium-YAG laser and electrofulguration.

The case reports of 40 patients with obstructive esophageal cancer treated with electrofulguration (EF) or neodymium (Nd)-YAG laser were reviewed. Surgery was contraindicated because of advanced carcinoma (17 patients), recurrence after resection (13 patients), recurrence after irradiation (four patients), and poor medical condition (four). Two patients refused surgery. There were 31 men and four women; mean age was 62 years. There were 31 adenocarcinomas, eight squamous cell carcinomas, and one metastatic breast carcinoma. Tumor locations were lower esophagus in 35 patients, middle esophagus in three, and cervical esophagus in two. Thirty-five patients had obstructions; two, bleeding, and three, both. None of the patients could swallow solids. A total of 255 treatments were given (mean, 6.6 per patient). The mean number of Nd-YAG treatments was 1.9; for EF, 1.3. All 40 patients tolerated solid food after treatment and the esophagus remained open from three to 14 weeks. Mean survival from first treatment was 11 months; from diagnosis, 17 months. Both techniques were safe and effective.

Adult↗
PubMed1989

A standard procedure for measuring rodent bedding particle size and dust content.

Hardwood dust can cause dermatitis, respiratory disease, allergies and nasal cancer in humans. A major concern with animal hardwood bedding is its dust content and its possible effects on animals and animal technicians. Previous reports on the quality control of rodent bedding did not specify sample size or shake time for measuring bedding particle size and dust content. These variables could alter particle size analyses. In an effort to more accurately characterize bedding particle size and dust content, 50g and 100g samples of hardwood bedding were shaken for 0.5, 1, 2, 3, 4, or 5 minutes in a portable sieve shaker containing U.S. standard sieves (Nos. 8, 20, 30 and 50) to determine optimum sample size and shake time. Significant differences (P less than 0.05 or greater) were observed in the percent of bedding retained on a No. 8 sieve when 50g and 100g samples were taken for 30 seconds or for 1 minute. Samples shaken for 2 or more minutes did not show any statistical differences in the percent of bedding which was retained on or passed through the different sieves. Major differences occurred in the percent of bedding which was retained or passed through the different sieves, when the shake time was varied from 0.5 to 5 minutes. These results indicated that 0.5 or 1 minute was definitely not enough time to accurately measure bedding particle size and dust content and that the sample size and shake time must be consistent in order to accurately compare the particle size and dust content of different shipments of bedding or to compare bedding from different vendors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Three studies comparing performance of the ER-3A tubephone with the TDH-50P earphone.

Three studies compared the performance of the ER-3A Tubephone insert earphone and the TDH-50P-MX41/AR supra-aural earphone. The three factors addressed were: threshold differences in children 7 to 10 yr old compared to adults, differences in real ear attenuation, and threshold differences in the presence of high background noise levels. The influence of insertion depth of the ER-3A Tubephone was also investigated. Findings showed no significant threshold differences between children and adults, significantly better real ear attenuation for the ER-3A Tubephone, and significantly better thresholds for the ER-3A in the presence of high background noise levels. Most critically, there was a significant change in attenuation characteristics of the ER-3A Tubephone, which was dependent on the insertion depth of the ear-tip.

Adult↗
PubMed1988

Detection and characterization of human serum antibodies to polycyclic aromatic hydrocarbon diol-epoxide DNA adducts.

The presence of serum antibodies to the diol-epoxide DNA adducts of representative polycyclic aromatic hydrocarbons (PAH), chrysene, benz[a]anthracene and benzo[a]pyrene, was determined by ELISA using serum samples obtained from normal healthy individuals. Antibodies that reacted against PAH adducted-DNA, but not against PAH-adducted protein, were found in the serum of approximately 40% of the test individuals. Specificity analysis of the antibodies demonstrated that serological cross-reactions between the benzo[a]pyrene and the chrysene diol-epoxide adducts were present. Similar cross-reactivity between the benz[a]anthracene and the chrysene adducts was observed. Sera containing antibodies that were apparently specific for each of the three PAH-DNA adducts were also identified. The presence of antibodies to PAH-DNA adducts indicates both past exposure to these carcinogenic PAH and their metabolic activation to the DNA damaging metabolites. These antibodies may prove to be useful in both retrospective and prospective epidemiological studies of various diseases associated with PAH exposure.

Adult↗
PubMed1988

Simultaneous administration of measles-mumps-rubella vaccine with booster doses of diphtheria-tetanus-pertussis and poliovirus vaccines.

The safety and efficacy of simultaneous administration of measles-mumps-rubella (MMR), diphtheria-tetanus-pertussis (DTP), and trivalent oral poliovirus (OPV) vaccines in a test group of 405 children were compared with the safety and efficacy of sequential administration of the same vaccines in a control group of 410 children given MMR followed by booster doses of DTP and OPV 2 months later. The study was double blind and placebo controlled with respect to DTP and OPV. Seroconversion rates to measles, mumps, and rubella exceeded 96% in both groups. Geometric mean titers to measles (P = .05) and rubella (P = .004) were higher in the test group, and titers of antibodies to the other seven antigens were similar in both groups. Clinical reaction data were analyzed in 248 of 405 test children and 249 of 410 control children. The rates of serious vaccine-associated reactions were low and similar in the two groups. Some minor side effects were reported more frequently in the test group, but these differences were judged to be related to study design rather than to differences in the safety of the two vaccine schedules. The results indicate that the safety and serologic efficacy of administering MMR simultaneously with reinforcing doses of DTP and OPV in the second year of life is equivalent to the safety and efficacy observed after administering these antigens separately.

Antibodies↗
PubMed1987

Thymidylate synthase gene amplification in a colon tumor resistant to fluoropyrimidine chemotherapy.

We have identified amplification of the thymidylate synthase gene in a colonic tumor that had developed resistance to 5-fluorouracil/leucovorin combination chemotherapy. The tumor had previously undergone a partial response to this combination but began to progress following a prolonged period of continuous therapy and relative disease stabilization. Since thymidylate synthase is a target enzyme for 5-fluorouracil, it is likely that the observed gene amplification is responsible for the resistance. Thus, gene amplification may be a relevant mechanism of acquired resistance to fluoropyrimidine chemotherapy in the clinic.

Colonic Neoplasms↗
PubMed1986

Surgical treatment of stenosis of the external auditory canal.

Analysis of the outcomes of reconstruction for stenosis of the ear canal in 20 patients revealed that the key step in the procedure after the stenotic meatus and ear canal skin have been removed (in the process accomplishing a wide meatoplasty) is widening the posterior bony canal wall until some mastoid cells are encountered. After the tympanic membrane has been deepithelialized, the bony canal should be lined with two separate pieces of split-thickness skin grafts and protected with Silastic sheeting and packing. Average follow-up of 3 1/3 years revealed that 2 ear canals have restenosed, 2 have partially restenosed, and 18 have healed. Of the 22 ears, 15 have had hearing improved to within 25 dB SRT or better, 5 have moderate hearing improvement, and 2 have no improvement. There were no complications.

Adolescent↗