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Biomedical subjects

A Davis

Publications and source records attributed to A Davis.

At least 199 records · Page 11Linked to original sources
PubMed1994

Microtubule dynamics modulated by guanosine triphosphate hydrolysis activity of beta-tubulin.

Microtubule dynamic instability underlies many cellular functions, including spindle morphogenesis and chromosome movement. The role of guanosine triphosphate (GTP) hydrolysis in dynamic instability was investigated by introduction of four mutations into yeast beta-tubulin at amino acids 103 to 109, a site thought to participate in GTP hydrolysis. Three of the mutations increased both the assembly-dependent rate of GTP hydrolysis and the average length of steady-state microtubules over time, a measure of dynamic instability. The fourth mutation did not substantially affect the rate of GTP hydrolysis or the steady-state microtubule lengths. These results demonstrate that the rate of GTP hydrolysis can modulate microtubule length and hence dynamic instability.

Amino Acid Sequence↗
PubMed1994

Biliary bile acid profiles in patients with familial adenomatous polyposis before and after colectomy.

The development of colorectal polyps and cancer in patients with familial adenomatous polyposis (FAP) is directly linked to inactivation of the APC gene. Other, epigenetic, mechanisms may be involved in tumorigenesis and a previous study suggested that an intrinsic difference in the biliary bile acid profile of untreated patients with FAP persisted after colectomy. Gas chromatography and gas chromatography-mass spectrometry were used to examine the biliary bile acid profiles of four groups of patients with normal gallbladders: 20 patients with an intact colon comprising 12 with FAP and eight controls; and 26 patients after colectomy comprising 12 with FAP and 14 controls. Comparison of ten different bile acids from both amidate fractions (glycine and taurine) revealed a small increase in the molar percentage of a minor bile acid (12-oxolithocholic acid) in patients with FAP and an intact colon compared with the matching control group. Colectomy was associated with a dramatic reduction in levels of secondary bile acids but with little difference between patients with FAP and controls.

Adenomatous Polyposis Coli↗
PubMed1994

Unconjugated faecal bile acids in familial adenomatous polyposis analysed by gas-liquid chromatography and mass spectrometry.

Previous studies have suggested reduced formation of secondary bile acids in patients with familial adenomatous polyposis (FAP). Developments in the collection, extraction and analysis of faecal bile acids as well as in the accurate diagnosis of FAP by DNA markers prompted reinvestigation of this hypothesis. The median (interquartile range (i.q.r.)) faecal bile acid concentration (3.69 (1.66-5.36) mumol per g dry weight) and daily excretion rate (60.5 (29-149) mumol per g per 24 h) in ten patients with FAP were similar to those of nine control subjects (3.31 (0.65-8.38) mumol per g dry weight and 30.1 (7.9-228) mumol per g per 24 h). Although the median (i.q.r.) concentration of only one bile acid (12-oxo-lithocholic acid) was significantly different between patients with FAP and controls (49 (34-70) versus 0 (0-20) nmol per g dry weight, P = 0.006), the derivatives of chenodeoxycholic acid (3.35 (1.76-5.32) versus 0.51 (0.13-2.37) mumol per g dry weight, P = 0.02) and cholic acid (1.63 (0.42-2.34) versus 0.80 (0.13-3.57) mumol per g dry weight, P = 0.006) were increased in those with polyposis. These results show increased bacterial biotransformation of faecal bile acids in patients with FAP.

Adenomatous Polyposis Coli↗
PubMed1994

Histological necrosis in soft tissue sarcoma following preoperative irradiation.

Forty-eight patients with soft tissue sarcomas that presented adverse features for treatment by limb salvage surgery and postoperative irradiation were treated by preoperative irradiation and surgery using a consistent protocol. Following resection, the extent of histological necrosis in the specimen was scored according to the criteria of Willet et al. Of the 48 cases, 16 (34%) demonstrated Grade 1 response (< 50% necrosis), 15 (31%) Grade 2 (50-80% necrosis), and 17 (35%) Grade 3 (> 80% necrosis). There was a trend toward more extensive necrosis in liposarcoma tumors (53% showing Grade 3 response compared to 26% of other sarcomas). Logistic regression analysis demonstrated a significant relationship between necrosis and tumor size (P < 0.001) with larger tumors having higher grades of necrosis. Tumor grade did not seem to affect the extent of necrosis. In comparison to the previous report of necrosis in soft tissue sarcoma following irradiation, the current analysis revealed a smaller proportion of tumors with Grade 3 necrosis.

Adult↗
PubMed1994

Aggressive fibrous tissue lesions in the upper extremity: treatment and results.

The oncologic and functional results of treatment of aggressive fibromatosis were reviewed in 16 patients. Five had undergone previous resections. Complete surgical excision, the recommended primary treatment modality for aggressive fibromatosis tissue lesions, could only be performed in five patients. Radiation was administered in 13 patients and mainly used when the resection margins were positive. One patient required reoperation for recurrence. Complete detailed follow-up data were available in 15 patients. Functional analysis revealed 11 good-excellent, 2 fair, and 2 poor results using the Enneking classification. Local control was achieved with a combination of surgery and radiation, maintaining good-excellent function in most patients. The local nature of this tumor can be controlled with surgery and radiation while preserving function in the upper extremity.

Adult↗
PubMed1994

Fresh osteochondral allografts for advanced giant cell tumors at the knee.

Sixteen patients with advanced giant cell tumors presenting at the knee were treated with complete tumor resection and reconstruction using fresh osteochondral allografts. All patients had one or more of the following indications for tumor resection (as opposed to curettage): tumor recurrence, pathologic fracture, or destruction of the subchondral bone plate. At the 3-15-year follow-up period (mean, 9 years), two grafts have been revised to second fresh grafts because of fracture and one graft has been converted to an allograft-implant composite reconstruction. One joint was fused because of late infection. Functional assessment was carried out in 13 patients, and 8 were good or excellent, 4 were fair, and 1 was poor. The authors conclude that the fresh osteochondral allograft is a viable treatment alternative to prosthetic arthroplasty in advanced, benign, aggressive bone tumors.

Adult↗
PubMed1994

Local control of soft tissue sarcoma of the extremity: the experience of a multidisciplinary sarcoma group with definitive surgery and radiotherapy.

Data gathered on 62 patients with soft tissue sarcoma of an extremity, treated in entirety by an experienced multidisciplinary sarcoma group, were analysed. With a philosophy of emphasising attainment of histologically negative margins at carefully planned limb sparing surgery, combined with either pre-operative or postoperative radiation therapy, a crude local control rate of 95% (59 of 62 patients) at a minimum of 24 months follow-up was obtained. Of 9 patients with microscopically positive margins after definitive surgery, 8 had undergone maximal resection compatible with preservation of function. One of these 9 failed locally, indicating that radiation therapy is effective in eradicating microscopic disease in this tumour. The excellent local control obtained with limb-sparing surgery in this series justifies early referral of patients with these uncommon cancers to an experienced multidisciplinary unit. 26 patients (42%) failed systemically at a minimum of 24 months follow-up, and 19 (30.6%) died of their disease, confirming the need for effective systemic therapy in soft tissue sarcoma. Tumours greater than 10 cm in diameter had a greater risk of systemic relapse.

Adolescent↗
PubMed1994

Handedness as a function of twinning, age and sex.

Questions about twin birth, sex, age and handedness for writing were asked as part of a survey of hearing disability (Davis, 1989) in a large sample of the adult population. The findings show unequivocally that the prevalence of left handedness is higher in twins than in the singleborn, in males than in females and in younger than in older adults. There was a marked and regular decline in the percentage of left writers with increasing age, but the effects for twinning and sex were evident in all of 7 age bands from 18 years to 80+. The findings are consistent with the assumption of the right shift theory of handedness (Annett, 1972, 1985) that the rs+ gene is expressed more strongly in females than in males, and in the singleborn than in twins.

Adolescent↗
PubMed1994

Medical education about substance abuse: changes in curriculum and faculty between 1976 and 1992.

PURPOSE: To examine changes in substance abuse education in U.S. medical schools between 1976 and 1992. METHODS: In 1991-92 the authors conducted a 16-year follow-up survey of six clinical departments in each of the 126 U.S. medical schools. Two previous surveys by scholars and surveys conducted by the Liaison Committee on Medical Education, Association of American Medical Colleges, and the National Center for Medical Fellowships in the Addictions provided baseline data for comparison. The statistical methods used in the comparisons were paired t-tests, one-way analyses of variance, and tests of differences between proportions. RESULTS: Significant increases were found in the numbers of required and elective curriculum units for medical students between 1986-87 and 1991-92. The number of medical schools requiring courses in substance abuse treatment increased from five to eight between 1986-87 and 1991-92. For residents, there were significant increases in the numbers of curriculum units for residents in family medicine and pediatrics. The average number of faculty in the 116 medical schools that reported units on substance abuse was 4.1. There were 45 fellowships in addiction medicine identified in 1991-92, with a total of 61 fellows in training. CONCLUSION: While the findings confirm positive changes, the amount of curricula time and the number of faculty having expertise in substance abuse education do not compare well with the amounts of time and numbers of faculty involved in clinical problems of similar prevalence, such as cancer and heart disease.

Curriculum↗
PubMed1994

Wound-healing complications after soft-tissue sarcoma surgery.

One-hundred and eighty patients undergoing limb-salvage surgery for soft-tissue sarcoma from 1986 to 1991 were assessed retrospectively for risk factors associated with major wound-healing complications. Twenty-three of 137 patients (16 percent) treated with primary direct wound closure sustained complications. In univariate analysis, the cross-sectional area of tumor resection, the use of preoperative irradiation, the width of the skin excision, a history of smoking, and a history of diabetes and/or vascular disease were associated with wound failure. Multivariate analysis revealed that preoperative irradiation (p = 0.04) and resection diameter (p = 0.017) accounted for the risk of complications. Eighteen additional patients were treated empirically with distant vascularized tissue transfer following preoperative irradiation because of concerns regarding potential wound complications. The lower complication rate in this group suggested that vascularized tissue transfer may be beneficial in lowering wound complication rates.

Adolescent↗
PubMed1994

AIDS and behavioural risk factors in women in inner city Baltimore: a comparison of telephone and face to face surveys.

STUDY OBJECTIVE: The study aimed to investigate the influence the mode of administration of a questionnaire (telephone or face to face) on reports of sexual behaviour and attitudes of HIV risk among woman of reproductive age. DESIGN: Two cross sectional surveys--one, a modified random digit dialing telephone survey, the second, a face to face street sample--were carried out by the same interviewers using similar questionnaires in the same neighbourhoods. SETTING AND PARTICIPANTS: Two socially deprived, inner city neighbourhoods of Baltimore City were assessed in early 1990 before a community health intervention was carried out in one of them. Women between 17 and 35 years were surveyed. MAIN RESULTS: Altogether 775 and 416 women in the target age group were interviewed by telephone and face to face methods: the response rates were 66.4% and 77% respectively. Telephone respondents tended to be older, had more education, were more often married, were less likely to live in subsidised housing, and were more likely to report HIV testing. The proportions of respondents who reported a previous abortion and had had a surgical sterilisation were higher among the telephone respondents (34.7% v 24.1% and 26.4% v 20.6%, respectively). With regard to sexual risk behaviour, the only statistically significant differences were found in the proportion who reported having used drugs (10.6% of the face to face v 2.4% of the telephone sample) or alcohol (30.5% v 16.3%) at last sexual intercourse. The observed method effect on these variables remained unchanged after adjusting for age, education, employment, and marital status. This effect was even stronger for a subgroup of face to face respondents who reported not having a telephone at home. The adjusted odds ratios for reporting alcohol consumption and use of drugs at the last sexual encounter in this group compared with the telephone respondents were 3.7 (2.1, 6.6) and 14.1 (5.7, 34.5) respectively. CONCLUSIONS: Despite the socioeconomic bias associated with the mode of data collection, there are only a few differences between the telephone and personal survey methods in reports of sexual behaviour. These differences are mostly concentrated in young women (under 20 years), and in a particularly socioeconomically deprived subgroup identified through telephone ownership.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Ethical reasoning concerning the feeding of severely demented patients: an international perspective.

Structured interviews were held with 149 registered nurses in seven countries in America, Asia, Australia and Europe concerning the feeding of severely demented patients who do not accept food. The most common reasons for nurses being willing to change their decision to feed or not to feed were an order from the medical head, a request from the patient's husband and/or the staff meeting. There was a connection between the willingness to feed and the ranking of ethical principles. Nurses who were most prone to feed the patient most often gave a high rank to the ethical principle of sanctity of life, while those who primarily chose not to feed the patient gave a high rank to the ethical principle of autonomy. All nurses stressed the ethical principle of beneficence.

Adult↗
PubMed1994

[The lidocaine test in tinnitus. Determination of its current status].

Intravenous administration of high doses of lidocaine has been used as a treatment modality for tinnitus. From 1991 to 1992 we treated 108 patients with high-dose lidocaine and had each patient complete a special tinnitus questionnaire. The effects of therapy were estimated on patients' subjective responses concerning loudness, suppression, stress relationships and mastering of tinnitus. These parameters were recorded before and after 5 days of lidocaine therapy. Quantification of tinnitus in acute and chronic disease showed significant temporary diminution of tinnitus in all patients. Complete alleviation of tinnitus was so impressive that personal attitudes concerning tinnitus were changed. These findings demonstrated that lidocaine was a useful strategy for significant relief of symptoms due to tinnitus.

Administration, Oral↗
PubMed1994

Faculty development in addiction medicine: project SAEFP, a one-year follow-up study.

BACKGROUND AND OBJECTIVES: The goal of Project SAEFP (Substance Abuse Education for Family Physicians, pronounced SAFE) was to increase the number of residency teaching faculty with expertise in addiction medicine. This paper reports the results of a 12-month follow-up study conducted to assess changes in residency teaching and clinical practice of 165 residency teaching faculty who participated in this project. METHODS: The Project SAEFP work group conducted a series of 5-day courses in the fall of 1990 at 10 sites around the country. The 165 faculty participants were taught how to use a set of 12 residency teaching modules that focused on clinical areas important to primary care physicians. The follow-up study consisted of a structured telephone interview. The findings were compared to previous interviews conducted before, and 3 months after, faculty participation in the course. RESULTS: The findings suggest long-term increases in the amount of teaching, clinical practice, and consultations conducted by the family medicine faculty who participated in this faculty development project. CONCLUSION: The findings of this study suggest that an intensive 5-day course using learner-centered teaching techniques can have a significant impact on primary care teaching faculty.

Adult↗
PubMed1994

Thyroid disease in the elderly. Part 1. Prevalence of undiagnosed hypothyroidism.

BACKGROUND: The purpose of this study was to examine the prevalence of previously unrecognized hypothyroidism in elderly patients. METHODS: The study was conducted in a primary care geriatrics clinic. Three hundred seventy elderly patients (287 women, 83 men) between 60 and 97 years of age were included in the study. Medical records of patients were reviewed retrospectively. Serum thyroid-stimulating hormone (TSH), free thyroxine (T4), height, weight, demographic variables, clinical signs and symptoms of hypothyroidism, history of thyroid diseases and treatment with thyroid medications, comorbidities, and current medications were obtained from the medical records. Patients who had both elevated TSH levels (5.0 to 14.9 microU/mL) and normal free T4 levels (0.7 to 2.0 ng/dL) met the criteria for "subclinical hypothyroidism." The criteria for "overt hypothyroidism" were TSH levels > or = 15 microU/mL and low free T4 levels (< 0.7 ng/dL). RESULTS: At the initial visit to the clinic, 18.1% of the patients (62 female and 5 male) had an established history of past or current thyroid disease. Another 20 women (5.4%) had a history of thyroid surgery. Of the remaining 283 patients with no history of thyroid disease, 14.6% of the women and 15.4% of the men had subclinical hypothyroidism. Overt hypothyroidism was discovered and subsequently treated in two female patients and one male patient (1.0% and 1.3%, respectively). Thyroid status was not significantly related to age group (60 to 64 years; 65 to 74; 75 to 84; 85 and older). Comorbidities typically associated with hypothyroidism were no more prevalent in hypothyroid patients than in euthyroid patients. CONCLUSIONS: We found a high prevalence of newly diagnosed subclinical hypothyroidism in both elderly male and female patients. Thyroid status was not related to age or to coexisting diseases. The clinical significance of treating subclinical hypothyroidism merits investigation.

Aged↗