Application of the Population Health Approach to Drinking Water System Surveillance

A drinking water supply is a complicated system in its construction,operation,maintenance and need for public health surveillance.     

Hybrid tumours of the salivary glands. A report of two cases involving the palate and a review of the literature

Hybrid tumours are very rare salivary gland lesions composed of two or more different tumoural entities in a single neoplasm that arise within a definite topographical region. In most cases adenoid cystic carcinoma has been the predominant component in these lesions. In this study we describe two patients with hybrid tumours located in the palate, one in a 49-year-old woman and one in a 71-year-old man. The first case involved adenoid cystic carcinoma and mucoepidermoid carcinoma, and the patient in the second case exhibited adenoid cystic carcinoma and epithelial-myoepithelial carcinoma. Both patients were treated with surgery and radiotherapy, and there has been no evidence of recurrence after 13 and 36 months of follow-up, respectively. The recognition of the histologic component with the higher grade of malignancy in every case of hybrid tumour of the salivary glands is a necessary step to determine the biological behaviour and, consequently, to determine the proper therapeutic approach.     

Absence of insulin receptor gene mutations in three insulin-resistant women with the polycystic ovary syndrome

Women with polycystic ovary syndrome (PCOS) are markedly insulin-resistant, but the molecular mechanisms of these changes and their relationship to the hyperandrogenic state remain to be clarified. Mutations have recently been identified in the insulin receptor gene of patients with extreme forms of insulin resistance associated with hyperandrogenism (eg, type A insulin resistance), and these mutations account for the insulin resistance in such patients. We performed this study to determine whether mutations in the coding portion of the insulin receptor gene were responsible for insulin resistance in PCOS. Insulin binding studies using cultured skin fibroblasts of three obese (body mass index > 27 kg/m²) women with PCOS (ie, mild hyperandrogenemia and chronic anovulation of unknown etiology) and documented insulin resistance showed no apprarent abnormalities in either the number or affinity of insulin binding sites. Direct sequencing of all 22 exons of the insulin receptor gene from two of the women with PCOS did not reveal any mutations. Furthermore, both alleles of the gene were expressed at equal levels. In a third insulin-resistant PCOS woman, there was no evidence for a mutation in the coding portion of the insulin receptor gene as determined by denaturing gradient gel electrophoresis (DGGE). We conclude that the insulin resistance in these PCOS women was caused by a defect extrinsic to the insulin receptor.     

Loss of cables, a novel gene on chromosome 18q, in ovarian cancer.

Cables, a cyclin-dependent kinase (cdk) interacting protein, has recently been identified and mapped to human chromosome 18q11. Cables appears to be primarily involved in cell cycle regulation and cell proliferation. Overexpression of Cables in Hela and other cell lines inhibits cell proliferation and tumor formation. We hypothesize that loss of Cables expression is associated with ovarian cancer. To test our hypothesis, we examined Cables expression in the four most common subtypes of ovarian carcinomas: serous, endometrioid, mucinous, and clear cell. In addition, mucinous and serous borderline tumors were also included. Loss of Cables expression was observed at high frequency in ovarian serous (11 of 14 cases, 79%) and endometrioid (5 of 10 cases, 50%) carcinomas. In contrast, strong Cables staining was detected in all clear cell carcinomas (10 cases) and mucinous tumors (5 carcinomas and 5 borderline tumors). The majority of serous borderline tumors (11 of 14 cases, 79%) showed positive Cables staining, with the rest showing focal loss of Cables expression. Furthermore, RT-PCR revealed the lack of Cables mRNA in a human ovarian cancer xenograft. No correlation was noted between loss of Cables and histologic grade, tumor stage, and survival. In conclusion, our results indicate that loss of Cables is common in ovarian serous and endometrioid carcinomas and imply that Cables may be involved in the pathogenesis of these two types of ovarian carcinomas.     

Genetic variability in the Guahibo population from venezuela

Four communities from Guahibo of Venezuela were analyzed for the genetic variants of nine erythrocyte enzymes and five serum proteins. Of the 14 loci determined, four were monomorphic. Significant frequency differentiation among communities, was present for ESD and TF markers. In general, Guahibo allele frequencies are in the variation ranges described for South American groups. The analysis indicates a relatively higher affinity of Guahibos with other Venezuelan groups within an irregular pattern of genetic distances that are likely related to the complex demographic history of the South American groups. Genetic diversity estimates reveal a moderate degree of genetic structure between the four Guahibo communities. This intra‐tribal variability in Guahibo appears to be lower than in Venezuelan Piaroa but higher than in other Amerindians and could be attributed to a combined effect of low population size and relative isolation of communities. At a continental level, the distribution of genetic diversity is consistent with preferential population movements along the eastern and western coastal areas. Am. J. Hum. Biol. 14:21–28, 2002. © 2002 Wiley‐Liss, Inc.     

Contractile properties of in situ perfused skeletal muscles from rats with congestive heart failure

We hypothesized that in congestive heart failure (CHF) slow-twitch but not fast-twitch muscles exhibit decreased fatigue resistance in the sense of accelerated reduction of muscle force during activity. Experiments were carried out on anaesthetized rats 6 weeks after induction of myocardial infarction or a sham operation (Sham). Animals with left ventricular end-diastolic pressure (LVEDP) > 15 mmHg under anaesthesia were selected for the CHF group. There was no muscle atrophy in CHF. Force generation by in situ perfused soleus (Sol) or extensor digitorum longus (EDL) muscles was recorded during stimulation (trains at 5 Hz for 6 s (Sol) or 10 Hz for 1.5 s (EDL) at 10 or 2.5 s intervals, respectively) for 1 h in Sol and 10 min in EDL at 37 °C. Initial force was almost the same in Sol from CHF and Sham rats, but relaxation was slower in CHF. Relaxation times (95–5 % of peak force) were 177 ± 55 and 131 ± 44 ms in CHF and Sham, respectively, following the first stimulation train. After 2 min of stimulation the muscles transiently became slower and maximum relaxation times were 264 ± 71 and 220 ± 45 ms in CHF and Sham, respectively (   P < 0.05  ). After 60 min they recovered to 204 ± 60 and 122 ± 55 ms in CHF and Sham, respectively (   P < 0.05  ). In CHF but not in Sham rats the force of contraction of Sol declined from the second to the sixtieth minute to 70 % of peak force. The EDL of both CHF and Sham fatigued to 24–28 % of initial force, but no differences in contractility pattern were detected. Thus, slow-twitch muscle is severely affected in CHF by slower than normal relaxation and significantly reduced fatigue resistance, which may explain the sensation of both muscle stiffness and fatigue in CHF patients.     

Tissue characterization of symptomatic and asymptomatic disc herniations by quantitative magnetic resonance imaging

The purpose of this investigation was to determine differences in tissue composition of symptomatic and asymptomatic disc herniations as reflected in T₁ and T₂ relaxation times (quantitative magnetic resonance investigation of the lumber spine. The longitudinal and transverse magnetic rlaxation times (T₁ and T₂, respectively) were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different repetition time values on a commercial whole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T₁ and T₂ relaxation times. Symptomatic disc herniations exhibited significantly (p_T1 < 0.04 and p_T2 < 0.003) shorter T₁(ΔT₁:–182.1 milliseconds, ?15%) and T₂(ΔT₂: ?11.0 milliseconds, ?21%) relaxation times than matched asymptomatic herniations. Symptomatic disc herniations also exhibited more advanced disc degeneration as graded by Pearce's criteria (p < 0.01). These results suggest that symptomatic and morphologically matched asymptomatic disc herniations differ with regard to disc matrix composition.