Physiological factors associated with low bone mineral density in female endurance runners

OBJECTIVE

To explore potential factors that could be associated with low bone mineral density (BMD) in female endurance runners.

METHODS

Fifty two female endurance runners (1,500 m to marathon), aged 18-44 years, took part. Body fat percentage, lumbar spine BMD, and femoral neck BMD were measured using the Hologic QDR 4,500w bone densitometer. Data on training, menstrual cycle status, osteoporosis, and health related factors were obtained by questionnaire. Dietary variables were assessed from a prospective seven day dietary record of macronutrients and micronutrients.

RESULTS

The mean (SD) lumbar spine and femoral neck BMD were 1.11 (0.11) and 0.89 (0.12) g/cm(2) respectively. A backward elimination regression analysis showed that age, body mass, body fat, distance run, magnesium, and zinc intake were the variables significantly associated with BMD. Lumbar spine BMD (g/cm(2)) = -1.90 + (0.0486 x age (years)) + (0.342 x log mass (kg)) - (0.000861 x age(2) (years)) - (0.00128 x distance (km/week)), with an R(2) = 30.1% (SEE = 0.089 (95% confidence interval (CI) 0.05 to 0.23); p<0.001). Femoral neck BMD (g/cm(2)) = -2.51 - (0.00989 x age (years)) + (0.720 x log mass (kg)) + (0.000951 x magnesium (mg/day)) -(0.0289 x zinc (mg/day)) - (0.00821 x body fat (%)) - (0.00226 x distance (km/week)), with an R(2) = 50.2% (SEE = 0.100 (95% CI 0.06 to 0.22); p<0.001). The negative association between skeletal BMD and distance run suggested that participants who ran longer distances had a lower BMD of the lumbar spine and femoral neck. Further, the results indicated a positive association between body mass and BMD, and a negative association between body fat and BMD.

CONCLUSIONS

The results suggest a negative association between endurance running distance and lumbar spine and femoral neck BMD, with a positive association between body mass and femoral neck and lumbar spine BMD. However, longitudinal studies are required to assess directly the effect of endurance running and body mass on BMD, and to see if the addition of alternative exercise that would increase lean body mass would have a positive effect on BMD and therefore help to prevent osteoporosis.

Removal of enteric viruses and selected microbial indicators by UV irradiation of secondary effluent

The Watercare Mangere Wastewater Treatment Facility, which treats wastewater from the greater Auckland New Zealand region, is undergoing a major expansion/upgrading to add advanced treatment and disinfection prior to discharge into a harbor. One important goal of this project is to protect the receiving water from microbial contamination. Since sufficient information on the fate of various microorganisms through wastewater treatment plants in New Zealand was not readily available, extensive pilot- and bench-scale studies were undertaken to develop specific design criteria for the treatment and disinfection systems. The specific objective of this study was to evaluate the removal and inactivation of enteric pathogens and other microbial indicators through treatment processes that employs UV irradiation as a final disinfection process. The removal of indicator organisms through secondary treatment was typically between 2.5-log (99.7% removal) and 2.8-log (99.8% removal) for fecal coliforms and enterococci, respectively. Indigenous F-specific bacteriophage exhibited a mean removal of 1.6-log (i.e. 97.7% removal) and Clostridium perfringens spores showed a mean removal of 1.3-log (i.e. 95% removal). The UV dose required to achieve a one log reduction in the concentration of indigenous F-specific bacteriophage was found to be approximately 20 mWs/cm2 per log removal. The concentration of enterovirus and adenovirus were consistently reduced to the limit of detection (1 TCID50/100L) at UV doses of 35 to 40 mWs/cm2 and 40 to 45 mWs/cm2, respectively. Clostridium perfringens spores were the most resistant indicator organisms, being reduced to less than 200 MPN/100 mL at a UV dose of 75 mWs/cm2.

Investigation of potential surrogate organisms and public health risk in UV irradiated secondary effluent

Watercare's Mangere Wastewater Treatment Plant in Auckland, New Zealand treats sewage from a population equivalent of approximately 1,000,000. The treatment plant is currently undergoing a major upgrade, and as a part of this upgrade the largest UV disinfection plant in the world (at the time of award of the contract) is being constructed. Pilot scale investigations were undertaken at a purpose built facility. The pilot plant employed secondary treatment, and filtration, UV disinfection and a number of low pressure membrane systems. Investigations at the facility focussed on attempting to identify relationships between potential surrogate indicator organisms (including enterococci, faecal coliforms, Clostridium perfringens spores and F-specific bacteriophage) and pathogenic organisms (including culturable human enteric viruses, bacterial pathogens and parasites). The aim of the study was to identify a suitable indicator organism and an associated effluent concentration that would ensure that an acceptable level of public health risk was maintained in the environment. The results showed that no suitable surrogate indicator organism could be found. However the results did indicate that a two tiered operating strategy, based on the concentration of enteroviruses present in raw sewage and an appropriate UV dose, would ensure that an acceptable level of public health risk was maintained in the environment.

Reproducibility of the blood lactate threshold, 4 mmol.l(-1) marker, heart rate and ratings of perceived exertion during incremental treadmill exercise in humans

The aim of this study was to investigate the reproducibility of blood lactate measurements, heart rate (HR) and ratings of perceived exertion (RPE) during treadmill exercise at speeds corresponding to the lactate threshold ( v(Th,la)-) and a fixed blood lactate concentration of 4 mmol.l(-1)( v(la)-(,4)). Possible differences in reproducibility related to fitness levels were also investigated. A group of 20 men [mean (SD)] [age 20.5 (1.4) years] and 16 women [age 21.2 (0.9) years] took part in the study. The subjects performed two identical incremental exercise tests consisting of at least six 4 min stages. Blood lactate concentrations, HR and RPE were recorded at the end of each stage. Limits of agreement (LoA), correlation coefficients and 95% confidence intervals for the mean difference between tests were employed to investigate the level of agreement and reproducibility of blood lactate concentration, HR and RPE. For the group as a whole, the sample correlation coefficient for speed at v(Th,la)- was r=0.88, and was r=0.92 for the speed at v(la)-(,4). At v(Th,la) -, the correlation coefficients for the moderately fit and unfit were r=0.94 and r=0.36, respectively, and at v(la)-(,4) r=0.93 and r=0.68, respectively. The LoA for the moderately fit group indicated that a change of 1.62 km.h(-1) in v(Th,la)- would be necessary to be considered a change in training status. For HR and RPE, relationships between the tests were generally poor. The LoA suggested that changes in scores must be unacceptably large. These findings cast doubt on the sensitivity of testing for change of blood lactate concentration, HR and RPE in this population.

Jamaica cancer mortality statistics, 1999

A total of 2697 cancer-related deaths were documented among Jamaicans for the year 1999, accounting for 17.7% of all deaths. Males accounted for 1466 and females for 1231. The age-adjusted cancer mortality rate was 171.7 per 100,000 for males, 122.0 per 100,000 for females and 140.5 per 100,000 for the total population. Leading cancer mortality sites for males were prostate, lung and stomach and in females, breast, cervix uteri and large bowel. Most deaths were recorded in the 55-64 and 65-74 year-age groups. Despite well-established cervical cancer screening programmes, the calculated mortality rate for cancer of the cervix uteri in Jamaican females (15.8 per 100,000) is approximately two and a half times that seen in African-American females.

Evaluation of the Leishmania recombinant K39 antigen as a diagnostic marker for canine leishmaniasis and validation of a standardized enzyme-linked immunosorbent assay

Canine infections with Leishmania infantum are important as a cause of serious disease in the dog and as a reservoir for human visceral leishmaniasis (VL). Accurate diagnosis of canine infections is essential to the veterinary community and for VL surveillance programs. A standardized ELISA using a purified recombinant antigen (rK39) specific to VL was compared to the immunofluorescent antibody test (IFAT) as the standard. The ELISA was developed, optimized and evaluated using sera from 6368 dogs. The standardized ELISA and IFAT results were highly concordant. The timing and pattern of ELISA and IFAT seroconversion in dogs followed prospectively after natural infections were very similar. Antibodies reacting with rK39 were more common in asymptomatic canine infections than reported for subclinical human VL. The rK39 ELISA is a relatively simple and rapid assay for assessing the infection status of dogs, and is an alternative to IFAT, especially when screening large numbers of samples.

Abnormal cobalamin-dependent transmethylation in AIDS-associated myelopathy

BACKGROUND

White matter vacuolization of the spinal cord is common in patients with AIDS and may lead to clinical manifestations of myelopathy. The pathogenesis of AIDS-associated myelopathy (AM) is unknown and may be related to metabolic abnormalities rather than to direct HIV infection. The striking pathologic similarity between AM and the vacuolar myelopathy associated with vitamin B(12) deficiency suggests that abnormal metabolism of the B(12)-dependent transmethylation pathway may be important in the pathogenesis of AM.

METHODS

The authors compared S-adenosyl-methionine (SAM), methionine, homocysteine, and glutathione in serum and CSF of 15 patients with AM vs. 13 HIV-infected controls without myelopathy (HWM). They also compared the results with a non-HIV--infected reference population (NC). All patients had normal B(12), folate, and methylmalonic acid levels.

RESULTS

There was a decrease in CSF SAM in the AM group compared with the HWM group (p < 0.0001) and the NC group (p < 0.0001). CSF SAM in the HWM group was also lower than that in the NC group (p = 0.015). Serum methionine was also reduced in serum of the myelopathic group compared with the NC group (p = 0.006).

CONCLUSIONS

AM is associated with an abnormality of the vitamin B(12)-dependent transmethylation pathway.

Radiofrequency ablation for unresectable hepatic tumors

BACKGROUND

Radiofrequency ablation (RFA) is a relatively new treatment for unresectable hepatic tumors. The purpose of this analysis was to examine the frequency of complications and local recurrence associated with RFA.

METHODS

Patients who underwent RFA of hepatic tumors with curative intent were included in this study. At laparotomy, RFA was performed using intraoperative ultrasound guidance. Computed tomography scans were obtained in the immediate postoperative period and every 3 to 6 months thereafter.

RESULTS

Forty patients underwent RFA for 122 hepatic tumors. Thirty-one patients had metastatic lesions from colorectal cancer; 9 had other liver tumors. Complications occurred in 8 patients. With 9.5 months median follow-up, 6 patients had local recurrence of their ablated tumors.

CONCLUSIONS

Our initial experience shows that RFA can effectively eradicate unresectable hepatic tumors. The rate and severity of complications appear acceptable. However, further study is necessary to assess long-term recurrence rates and effect on overall survival.

Utility of intraoperative frozen section analysis of sentinel lymph nodes in breast cancer

BACKGROUND

Intraoperative frozen section pathologic analysis of sentinel lymph node (SLN) may guide immediate (single-stage) completion axillary dissection for patients with nodal metastases.

METHODS

The results of 203 consecutive patients undergoing SLN biopsy who had intraoperative pathology consultation between January 1998 and September 2000 were reviewed. SLN were analyzed by standard frozen section procedures. Final pathologic analysis included hematoxylin and eosin (H&E) staining of serial sections at 2-mm intervals.

RESULTS

Frozen section analysis correctly identified a positive or negative result in 185 of 203 cases (overall accuracy 91%). In 17 of 53 cases, the SLNs were negative for tumor by frozen section, but positive on permanent section analysis (sensitivity 68%). The mean size of the nodal metastases was 6.2 mm and 1.5 mm in patients found to have true positive and false negative results, respectively (P <0.003). A single false positive SLN is reported.

CONCLUSIONS

Two thirds of the patients were spared the need for reoperative axillary lymphadenectomy.

The use of cytokeratin staining in sentinel lymph node biopsy for breast cancer

BACKGROUND

Controversy exists regarding the routine use of cytokeratin immunohistochemistry (IHC) in the histopathologic examination of breast cancer sentinel lymph nodes (SLN) because the clinical significance of micrometastases detected by IHC is unclear. This analysis was performed to determine the frequency of IHC-detected micrometastases.

METHODS

All patients underwent SLN biopsy, followed by completion axillary dissection. This analysis included patients who had SLN evaluated by IHC. SLN were examined by hematoxylin and eosin (H&E) stain at 2-mm intervals, with IHC in 2 sections. The axillary dissection specimen was evaluated by routine H&E staining.

RESULTS

IHC was performed in SLNs from 973 patients. Of the 869 patients with negative nodes by H&E, 58 (6.7%) were "upstaged" by IHC. In 6 of 58 patients (10.3%) who had IHC-only positive SLN, nodal metastases were found in the axillary dissection specimen.

CONCLUSIONS

IHC resulted in upstaging of 6.7% of patients who had negative SLN on H&E staining. These patients had a 10.3% risk of residual axillary nodal metastases. However, the clinical significance of IHC-only positive SLN requires further study.

Reliable lymphatic drainage to axillary sentinel lymph nodes regardless of tumor location within the breast

BACKGROUND

This analysis was performed in order to determine whether primary tumor location in breast cancer affects the axillary sentinel lymph node (SLN) identification (ID) rate, the false negative (FN) rate, incidence of axillary nodal metastases, or the number of SLN identified.

METHODS

In this prospective multi-institutional study, SLN biopsy was performed on clinical stage T1-2, N0 breast cancer patients using blue dye alone or in combination with radioactive colloid, followed by completion axillary LN dissection.

RESULTS

Central tumor location was associated with an improved FN rate, which may be related to reliable drainage from the subareolar lymphatic plexus. Tumor location did not significantly affect the SLN ID rate or the mean number of SLN identified. Medial tumor location was associated with a decreased rate of axillary nodal metastasis.

CONCLUSIONS

Breast cancers drain reliably to the axillary lymph nodes regardless of tumor location within the breast.

Defining the optimal surgeon experience for breast cancer sentinel lymph node biopsy: a model for implementation of new surgical techniques

OBJECTIVE

To determine the optimal experience required to minimize the false-negative rate of sentinel lymph node (SLN) biopsy for breast cancer.

SUMMARY BACKGROUND DATA

Before abandoning routine axillary dissection in favor of SLN biopsy for breast cancer, each surgeon and institution must document acceptable SLN identification and false-negative rates. Although some studies have examined the impact of individual surgeon experience on the SLN identification rate, minimal data exist to determine the optimal experience required to minimize the more crucial false-negative rate.

METHODS

Analysis was performed of a large prospective multiinstitutional study involving 226 surgeons. SLN biopsy was performed using blue dye, radioactive colloid, or both. SLN biopsy was performed with completion axillary LN dissection in all patients. The impact of surgeon experience on the SLN identification and false-negative rates was examined. Logistic regression analysis was performed to evaluate independent factors in addition to surgeon experience associated with these outcomes.

RESULTS

A total of 2,148 patients were enrolled in the study. Improvement in the SLN identification and false-negative rates was found after 20 cases had been performed. Multivariate analysis revealed that patient age, nonpalpable tumors, and injection of blue dye alone for SLN biopsy were independently associated with decreased SLN identification rates, whereas upper outer quadrant tumor location was the only factor associated with an increased false-negative rate.

CONCLUSIONS

Surgeons should perform at least 20 SLN cases with acceptable results before abandoning routine axillary dissection. This study provides a model for surgeon training and experience that may be applicable to the implementation of other new surgical technologies.