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Biomedical subjects

J W Martin

Publications and source records attributed to J W Martin.

At least 37 records · Page 2Linked to original sources
PubMed2000

Methylobacterium mesophilicum infection: case report and literature review of an unusual opportunistic pathogen.

Methylobacterium mesophilicum is a methylotrophic, pink pigmented, gram-negative rod that was initially isolated from environmental sources that is being increasingly reported as a cause of opportunistic infections in immunocompromised hosts. We present the case of an immunocompromised woman who developed a central catheter infection with M. mesophilicum and review the other 29 cases reported in the literature, noting that it is frequently resistant to beta-lactam agents but is generally susceptible to aminoglycosides and quinolones.

Adult↗
PubMed2000

Predicting cancer development in oral leukoplakia: ten years of translational research.

Our 10-year translational study of the oral premalignant lesion (OPL) model has advanced the basic understanding of carcinogenesis. Although retinoids have established activity in this model, a substantial percentage of our OPL patients progress to cancer, especially after treatment is stopped. On the basis of our 10-year OPL study, we have developed the first comprehensive tool for assessing cancer risk of OPL patients. This cancer risk assessment tool incorporates medical/demographic variables, epidemiological factors, and cellular and molecular biomarkers. Between 1988 and 1991, 70 advanced OPL patients were enrolled in a chemoprevention trial of induction with high dose isotretinoin (1.5 mg/kg/day for 3 months) followed by 9 months of maintenance treatment with either low dose isotretinoin (0.5 mg/kg/day) or beta-carotene (30 mg/d; total treatment duration, 1 year). We assessed the relationship between cancer risk factors and time to cancer development by means of exploratory data analysis, logrank test, Cox proportional hazard model, and recursive partitioning. With a median follow-up of 7 years, 22 of our 70 patients (31.4%) developed cancers in the upper aerodigestive tract following treatment. The overall cancer incidence was 5.7% per year. The most predictive factors of cancer risk are OPL histology, cancer history, and three of the five biomarkers we assessed (chromosomal polysomy, p53 protein expression, and loss of heterozygosity at chromosome 3p or 9p). In the multivariable Cox model, histology (P = 0.0003) and the combined biomarker score of chromosomal polysomy, p53, and loss of heterozygosity (P = 0.0008) are the strongest predictors for cancer development. Retinoic acid receptor beta and micronuclei were not associated with increased cancer risk. We have demonstrated a successful strategy of comprehensive cancer risk assessment in OPL patients. Combining conventional medical/demographic variables and a panel of three biomarkers can identify high risk patients in our sample. This result will need to be validated by future studies. With the identification of high risk individuals, more efficient chemoprevention trials and molecular targeting studies can be designed.

Alcohol Drinking↗
PubMed1998

Effect of partial release of the posterior cruciate ligament in total knee arthroplasty.

Appropriate tension of the posterior cruciate ligament, which often is tight in deep flexion, is difficult to achieve after posterior cruciate ligament retaining total knee arthroplasty. Kinematics and maximum flexion after partial release of the posterior cruciate ligament were evaluated in this study. A partial release improved the maximum flexion angle and maintained anteroposterior stability without causing undesirable changes in kinematics, whereas full resection of the posterior cruciate ligament caused unfavorable anteroposterior instability. Partial posterior cruciate ligament release eliminated excessive rollback movement caused by a tight posterior cruciate ligament and also shifted the point of articular surface contact anteriorly. These results indicate that partial release of the posterior cruciate ligament may improve knee function in patients with a tight posterior cruciate ligament after total knee arthroplasty.

Arthroplasty↗
PubMed1997

Brain asymmetry as a potential biomarker for developmental TCDD intoxication: a dose-response study.

Previous studies have indicated that in ovo exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds is correlated with the development of grossly asymmetric brains. This asymmetry is manifested as a difference between the two halves of the forebrain and the tecta. Previously, only wildlife species (heron, cormorant, and eagle) had been shown to manifest this response. In the wildlife studies, the frequency and degree of left-right interhemispheric differences had been correlated with the levels of polychlorinated dibenzo-p-dioxin toxic equivalency factors (TEFs) in eggs from the same nest (heron, cormorant). We studied the effect of in ovo exposure to TCDD on the brain throughout development in a sensitive laboratory model (chicken). Embryos from chicken eggs (Gallus gallus) injected with one of several doses of TCDD or vehicle control were sacrificed after 9, 11, 13, 15, 17, or 20 days of incubation, or incubated to hatch and then sacrificed either within 24 hr or at 3 weeks post-hatch. Measurements of both chicken embryo and hatchling brains indicated that 1) TCDD alone induced the brain asymmetry in developing chickens; 2) this brain asymmetry was similar to that observed in animals exposed in the wild to a mixture of TCDD-related contaminants; 3) there was a dose-related increase in both the frequency and severity of brain asymmetry observed at all ages measured; and 4) the asymmetry was measurable in embryonic brains at an age when the braincase was a thin, flexible layer (embryonic day 9), implying that the effect of TCDD was directly on the developing brain and not indirectly via an effect on the braincase.

Abnormalities, Drug-Induced↗
PubMed1997

Prosthetic rehabilitation of patients with advanced nonmelanoma skin cancer.

Attention to detail at all stages of treatment can ensure a successful prosthetic rehabilitation. This detail must be considered a priority at presurgery, surgery, and at every stage in fabricating the prosthesis. Teamwork between the surgeon and maxillofacial prosthodontist will ensure an optimal surgical preparation and definitive prosthesis. Evidence of interaction among team members most certainly can be encouraging to the patient. It is important that during the prosthetic phase of treatment, attention be made in terms of tissue assessment, impression making, sculpting, mold fabrication, familiarity with materials, appreciation of color, delivery of instructions, and patient education, which will ensure a satisfactory outcome. With the desire, determination, and encouragement from the restorative team to make the most of this artificial replacement, a patient can have a higher quality of life and a more normalized lifestyle.

Basal Cell Carcinoma↗
PubMed1997

Accumulation of p53 protein and retinoic acid receptor beta in retinoid chemoprevention.

Although retinoids have proven to be effective as chemopreventive agents in reversing premalignant oral lesions and preventing second primary tumors, their mechanisms of chemopreventive efficacy in clinical settings have not been established. To better define this mechanism, we studied p53 protein and retinoic acid receptor beta (RAR-beta) expression in 52 baseline biopsy samples taken from premalignant oral lesions. We then studied p53 expression in 39 matched samples and RAR-beta expression in 38 matched samples before and after treating them with isotretinoin. The study results were then compared with clinical responses. To detect p53 protein expression, 4-micrometer sections of formalin-fixed, paraffin-embedded tissue specimens were used for immunohistochemical analysis with a monoclonal anti-p53 antibody, and levels of p53 expression were recorded with a labeling index (LI). Expression of RAR-beta mRNA was determined using nonradioactive in situ hybridization, and the staining intensity of RAR-beta mRNA was semiquantitated using scores from 0 (no expression) to 3+ (highest expression). p53 protein was detected in 85% of all lesions. High p53 protein expression (LI >/= 0.2) was detected in 25% of the lesions at baseline and in 18% of the lesions after isotretinoin therapy. The clinical response was 65% for lesions having low p53 expression (LI < 0.2) and 27% for lesions having high p53 expression (P = 0.027). Expression of RAR-beta mRNA was detected in 40% of the patients at baseline and increased to 90% of the patients after isotretinoin therapy (P < 0. 001). Seventy-two percent of the patients having low p53 expression had no RAR-betamRNA expression at baseline, whereas 22% of the patients having high p53 expression had no RAR-beta expression, which suggests that patients having low p53 expression tended to lose RAR-beta mRNA expression in their tissues. Eighty-three percent of patients having low p53 expression had up-regulation of RAR-beta mRNA after isotretinoin therapy, compared with 22% of patients with high p53 expression (P = 0.003). We correlated baseline p53 protein expression with RAR-beta modulation and clinical responses to isotretinoin therapy. The patients with low p53 protein expression at baseline and up-regulation of RAR-beta after isotretinoin therapy achieved a 70% rate of major response. The patients with low p53 protein expression and either no change or down-regulation of RAR-beta or with high p53 expression and up-regulation of RAR-beta had a response rate of 50%. The patients with high p53 protein expression and either no change or down-regulation of RAR-beta had a response rate of only 14% to isotretinoin therapy. The basic mechanisms underlying the association between clinical responses and these two biomarkers need to be explored.

Adult↗
PubMed1996

A hybrid-mold technique for fabricating facial prostheses.

A hybrid-mold technique is described for fabricating facial prostheses with delicate contours and/or undercuts that require additional support. This quick and simple technique combines several common laboratory materials and protects select areas of the stone mold during prosthesis fabrication. This technique also extends the mold's years of service and the number of prostheses that can be fabricated from the mold.

Acrylic Resins↗
PubMed1996

Technique for fabricating a mirror-image prosthetic ear.

A simple technique for producing a mirror image of a cast for sculpting an auricular prosthesis is described. A transparency copy of the cast assist the operator in sculpting the contours of the facial prosthesis.

Ear, External↗
PubMed1996

Structure of the spiroketal-macrolide ossamycin.

Ossamycin is a cytotoxic agent of undetermined structure that was originally isolated in 1965 from culture broths of Streptomyces hygroscopicus var. ossamyceticus. Its overall structure and relative stereochemistry have now been determined by single crystal X-ray diffraction studies. Absolute stereochemistry was established according to the previously determined configuration of its aminosaccharide constituent, ossamine. The aglycone of ossamycin possesses a 24-membered macrolide ring system onto which is incorporated both a 6,6-spiroketal and 5-membered hemiketal ring system. The overall three-dimensional structure possesses features in common with the related macrocyclic antibiotics dunaimycin, cytovaricin, and A82548A.

Anti-Bacterial Agents↗
PubMed1996

Complete dentures for the obturator patient.

Treatment of the edentulous obturator patient requires the same basic fundamentals as used in the treatment of the complete-denture patient. Problems and considerations unique to the development, delivery, and follow-up of the complete maxillary obturator prosthesis and mandibular denture in the patient with an acquired maxillary defect are discussed. Combining laboratory and clinical research in maxillofacial prosthodontics and plastic and reconstructive surgery continues to improve the rehabilitation of these patients.

Denture Design↗
PubMed1995

Oral and dental management of the cancer patient: prevention and treatment of complications.

Aggressive cancer therapy places patients at greater risk for oral complications and treatment-related consequences. Unfortunately, prevention and/or treatment of such oral sequelae has become an often overlooked priority of the treatment team. We describe a philosophy of management of the cancer patient that specifically emphasizes the prevention and treatment of oral complications associated with cancer therapy. These concepts and principles are based on treatment protocols and ongoing clinical research at the University of Texas M.D. Anderson Cancer Center in Houston, Texas.

Clinical Protocols↗
PubMed1995

Technique for magnet replacement in silicone facial prostheses.

Magnets are often used in silicone facial prostheses for retention. However, these magnets may need to be replaced or repositioned as a result of loss, wear, or poor initial placement. Replacement can be easily accomplished by use of a nylon mesh material and a simple laboratory technique.

Humans↗
PubMed1995

Oral complications associated with aspergillosis in patients with a hematologic malignancy. Presentation and treatment.

Opportunistic mycotic infections, such as aspergillosis, can produce morbid consequences with or without aggressive therapy in an immunocompromised patient. Treatment including amphotericin B and resection of the infected tissue must be considered early in the overall management of the patient. We describe two patients with acute myelogenous leukemia who underwent intense cytoreductive therapy with bone marrow transplantation and an associated fungal infection treated with an investigational form of amphotericin B.

Adult↗
PubMed1995

Patient appointments during interim obturation: is it cost-effective?

PURPOSE: The purpose of this study was to quantify the number of patient appointments needed during the interim obturator service period in the Department of Dental Oncology at MD Anderson Cancer Center (Houston, TX). MATERIALS AND METHODS: A retrospective study evaluating 100 patient records of patients who underwent maxillectomies between 1989 and 1993. RESULTS: Of the 100 patients analyzed, 42 patients had a definitive prosthesis fabricated within 90 days after surgery. On average, 12 appointments (range, 6-24 appointments) were recorded for each patient during this 90-day global interim obturator period. CONCLUSIONS: The 12 appointments reflect a considerable amount of clinical and laboratory effort and reinforces the national concern of proper reimbursement.

Appointments and Schedules↗