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Biomedical subjects

Q Pan

Publications and source records attributed to Q Pan.

97 records · Page 6Linked to original sources
PubMed1985

Effects of carcinogen dosage on experimental colonic carcinogenesis by azoxymethane: an ultrastructural study of grossly normal colonic mucosa.

The transmission electron microscopic features of grossly normal colonic mucosa in the azoxymethane [(AOM) CAS: 25843-45-2]-treated rat model of colonic carcinogenesis were studied by the method of concomitant variation. Ten-week-old male F344 rats were given 10 weekly sc injections of AOM at doses of 3, 7, or 14 mg/kg body weight and were killed 1 week or 15 weeks after the last AOM dose. Grossly normal distal left colon was examined using transmission electron microscopy. Three transient dose-dependent features of colonic epithelial cells were identified: a) mitochondrial injury, b) nuclear pleomorphism and loss of polarity, and c) increased numbers of mitotic figures in the lower third of the crypts. Because these dose-dependent features were present only shortly after AOM administration, they appeared to be manifestations of carcinogen toxicity and associated reactive, regenerative epithelial changes. By contrast, four persistent dose-dependent features were identified: a) increased numbers of epithelial cells with enlarged nucleoli, b) increased numbers of mitotic figures in the middle third of crypts, c) reduced numbers of goblet cells, and d) reduced numbers of apical cytoplasmic vacuoles in the upper third of the crypts. Because these features persisted in a dose-dependent manner for many weeks after the last dose of AOM and were present after the latent period to tumor formation, they appear to be morphologic precursors to colonic carcinogenesis in the model.

Animals↗
PubMed1982

Silica fragments from millet bran in mucosa surrounding oesophageal tumours in patients in northern China.

Millet bran is a component of the diet in the area of highest oesophageal cancer incidence in northern China. Millet bran was found to contain up to 20% by weight of silica; some of this silica occurs as friable sheets or sharply-pointed fibres. These types of silica in millet bran are the most likely source of an unusual contamination with fragments of silica found in the oesophageal mucosa surrounding tumours in patients in northern China. A group of mucosal samples analysed together contained over 5,000 particles/g (100 parts per million by weight), ten times as many as were found in tissue from normal controls taken at necropsy in London. The modal diameter was 10 microgram (1-70 microgram). The particles were in the body of the mucosa and were not simply a surface contaminant. Silica fragments and fibres of similar size originating from other plant species occur in the diet in the two other regions of greatest incidence of oesophageal cancer, the Transkei and Iran. If such fragments enter the mucosa, they must cause some degree of trauma, and they may also be able to stimulate proliferation by providing anchorage. These findings suggest the possibility that silica particles might be involved in the aetiology of oesophageal cancer.

Adult↗
PubMedDate not supplied

Medication cost information in a computer-based patient record system. Impact on prescribing in a family medicine clinical practice.

BACKGROUND: Medications account for 8% of national health care expenditures, and prescription drugs are a focus of cost containment measures. Physicians have limited knowledge about drug costs, and no method of providing this information has demonstrated sustained cost reductions. OBJECTIVE: To determine the impact of cost information in a computer-based patient record system on prescribing by family physicians. METHODS: A yearlong, controlled clinical trial was conducted at the Family Medicine Center, Medical University of South Carolina, Charleston, a group practice staffed by attending physicians and residents. Prescription cost information was included in the computer-based patient record system used at the center. During a 6-month period, cost information was not displayed; during the subsequent 6-month intervention period, costs were displayed at the time of prescribing. An intention-to-treat analysis was used to compare prescription costs between the control and intervention periods for all medications prescribed, and stratified analyses for several medication and physician factors were performed. RESULTS: A total of 22,883 prescriptions were written during the 1-year study period. The mean +/- SD cost per prescription in the control period was $21.83 +/- $27.00 (range, $0.01-$510.00), and in the intervention period was $22.03 +/- $28.12 (range, $0.01-$435.96) (P = .61, Student t test). Increases in mean prescription cost and proportion of total costs were identified in 4 medication classes: antibiotics, cardiovascular agents, headache therapies, and antithrombotic agents. Decreases in mean prescription cost and proportion of total costs were identified in 5 medication classes: nonsteroidal anti-inflammatory drugs, histamine type 2-receptor antagonists and proton pump inhibitors, ophthalmic preparations, vaginal preparations, and otic preparations. CONCLUSIONS: In this setting, the provision of real-time computerized drug cost information did not affect overall prescription drug costs to patients, although differences in individual medication classes were observed. The negative results of this study may reflect confounding due to the use of historical controls, suboptimal timing of the intervention in the prescribing process, susceptibility bias at the study site, or the insensitivity of prescribing habits to cost information.

Drug Costs↗
PubMedDate not supplied

Antibiotics for upper respiratory tract infections. Follow-up utilization and antibiotic use.

OBJECTIVES: To examine the effects of antibiotic prescribing during an initial visit for viral respiratory tract infections on future care seeking and the cost of care. MATERIALS AND METHODS: Retrospective analysis of recorded visits for viral respiratory tract infections (N = 49,862) between January 1, 1995, and December 31, 1997, to practices in a large network of affiliated practices that use the same electronic medical record. RESULTS: Patients receiving antibiotics at the initial visit were less likely to return for a second visit, but this difference was small (15.4% vs 17.4%, P < .001). When returning for the second visit, those who received an antibiotic on the initial visit were prescribed more expensive antibiotics than those who had not received an antibiotic on the initial consultation. Overall, cost from initial antibiotic use outweighed any benefit from reduced utilization in adults and children. CONCLUSIONS: Antibiotic prescribing at an initial contact for a viral respiratory tract illness may reduce the likelihood that an individual will return for a subsequent visit, but adds substantial costs to care for the initial antibiotic and for more expensive antibiotics used on subsequent visits.

Adolescent↗
PubMedDate not supplied

Mutation analysis of hereditary multiple exostoses in the Chinese.

Hereditary multiple exostoses (EXT; MIM 133700) is an autosomal dominant bone disorder. It is genetically heterogeneous with at least three chromosomal loci: EXT1 on 8q24.1, EXT2 on 11p11, and EXT3 on 19p. EXT1 and EXT2, the two genes responsible for EXT1 and EXT2, respectively, have been cloned. Recently, three other members of the EXT gene family, named the EXT-like genes (EXTL: EXTL1, EXTL2, and EXTL3), have been isolated. EXT1, EXT2, and the three EXTLs are homologous with one another. We have identified the intron-exon boundaries of EXTL1 and EXTL3 and analyzed EXT1, EXT2, EXTL1, and EXTL3, in 36 Chinese families with EXT, to identify underlying disease-related mutations in the Chinese population. Of the 36 families, five and 12 family groups have mutations in EXT1 and EXT2, respectively. No disease-related mutation has been found in either EXTL1 or EXTL2, although one polymorphism has been detected in EXTL1. Of the 15 different mutations (three families share a common mutation in EXT2), 12 are novel. Most of the mutations are either frameshift or nonsense mutations (12/15). These mutations lead directly or indirectly to premature stop codons, and the mutations generate truncated proteins. This finding is consistent with the hypothesis that the development of EXT is mainly attributable to loss of gene function. Missense mutations are rare in our families, but these mutations may reflect some functionally crucial regions of these proteins. EXT1 is the most frequent single cause of EXT in the Caucasian population in Europe and North America. It accounts for about 40% of cases of EXT. Our study of 36 EXT Chinese families has found that EXT1 seems much less common in the Chinese population, although the frequency of the EXT2 mutation is similar in the Caucasian and Chinese populations. Our findings suggest a possibly different genetic spectrum of this disease in different populations.

China↗
PubMedDate not supplied

[Radiotherapy of cutaneous lymphomas].

Radiotherapy plays an important role in the treatment of cutaneous lymphomas. In the treatment of Mycosis fungoides, total skin electron beam radiation therapy is efficient for patients with limited and superficial forms of the disease. Radiotherapy is also efficient for the locally advanced forms of non-epidermotropic lymphomas. The palliative radiotherapy is indicated for advanced, nodular and treatment resistant forms of cutaneous lymphomas and for voluminous lymphadenopathies.

Electrons↗