Prenatal lead exposure in relation to age at menarche: results from a longitudinal study in Mexico City.

Animal and cross-sectional epidemiological studies suggest that prenatal lead exposure is related to delayed menarche, but this has not been confirmed in longitudinal studies. We analyzed this association among 200 girls from Mexico City who were followed since the first trimester of gestation. Maternal blood lead levels were analyzed once during each trimester of pregnancy, and daughters were asked about their first menstrual cycle at a visit between the ages of 9.8 and 18.1 years. We estimated hazard ratios (HRs) and 95% confidence intervals (CI) for probability of menarche over the follow-up period using interval-censored Cox models, comparing those with prenatal blood lead level ⩾5 µg/dl to those with prenatal blood lead <5 µg/dl. We also estimated HRs and 95% CI with conventional Cox regression models, which utilized the self-reported age at menarche. In adjusted analyses, we accounted for maternal age, maternal parity, maternal education, and prenatal calcium treatment status. Across trimesters, 36-47% of mothers had blood lead levels ⩾5 µg/dl. Using interval-censored models, we found that during the second trimester only, girls with ⩾5 µg/dl prenatal blood lead had a later age at menarche compared with girls with prenatal blood lead levels <5 µg/dl (confounder-adjusted HR=0.59, 95% CI 0.28-0.90; P=0.05). Associations were in a similar direction, although not statistically significant, in the conventional Cox regression models, potentially indicating measurement error in the self-recalled age at menarche. In summary, higher prenatal lead exposure during the second trimester could be related to later onset of sexual maturation.

Age at menarche in relation to prenatal rainy season exposure and altitude of residence: results from a nationally representative survey in a tropical country.

Intrauterine exposure to the rainy season in the tropics may be accompanied by high rates of infection and nutritional deficiencies. It is unknown whether this exposure is related to the extrauterine timing of development. Our aim was to evaluate the relations of prenatal exposure to the rainy season and altitude of residence with age at menarche. The study included 15,370 girls 10 to <18 years old who participated in Colombia's 2010 National Nutrition Survey. Primary exposures included the number of days exposed to the rainy season during the 40 weeks preceding birth, and altitude of residence at the time of the survey. We estimated median menarcheal ages and hazard ratios with 95% confidence interval (CI) according to exposure categories using Kaplan-Meier cumulative probabilities and Cox proportional hazards models, respectively. All tests incorporated the complex survey design. Girls in the highest quintile of gestation days exposed to the rainy season had an earlier age at menarche compared with those in the lowest (adjusted hazard ratios (HR)=1.08; 95% CI 1.00-1.18, P-trend=0.03). Girls living at altitudes ⩾2000 m had a later age at menarche compared with those living <1000 m (adjusted HR=0.88; 95% CI 0.82-0.94, P-trend <0.001). The inverse association between gestation days during the rainy season and menarche was most apparent among girls living at altitudes ⩾2000 m (P, interaction=0.04). Gestation days exposed to the rainy season and altitude of residence were associated with the timing of sexual maturation among Colombian girls independent of socioeconomic status and ethnicity.

Hyperbaric oxygen therapy attenuates central sensitization induced by a thermal injury in humans.

BACKGROUND: Hyperbaric oxygen (HBO2 ) treatment has in animal experiments demonstrated antinociceptive effects. It was hypothesized that these effects would attenuate secondary hyperalgesia areas (SHAs), an expression of central sensitization, after a first-degree thermal injury in humans. METHODS: Seventeen healthy volunteers were examined during two sessions using a randomized crossover design. Volunteers were studied during control conditions (ambient pressure, FI O2 = 0.21) and during HBO2 (2.4 standard atmosphere, FI O2 = 1.0, 90 min) conditions in a pressure chamber. Quantitative sensory testing, including assessment of SHAs was performed. RESULTS: A statistically significant overall attenuation of SHAs was seen during the HBO2 sessions compared with the control-sessions (P = 0.011). In the eight volunteers starting with the HBO2 session, no difference in SHAs compared with control was demonstrated. However, in the nine volunteers starting with the control session, a statistical significant attenuation of SHAs was demonstrated in the HBO2 session (P = 0.004). CONCLUSIONS: The results indicate that HBO2 therapy in humans attenuates central sensitization induced by a thermal skin injury, compared with control. These new and original findings in humans corroborate animal experimental data. The thermal injury model may give impetus to future human neurophysiological studies exploring the central effects of hyperbaric oxygen treatment.

Effect of acute and delayed hyperbaric oxygen therapy on cyanide whole blood levels during acute cyanide intoxication.

Cyanide and carbon monoxide, which are often found in fire victims, are toxic gases emitted from fires. Cyanide and carbon monoxide have similar molecular structure. Cyanide binds to the enzyme cytochrome oxidase a, a3 similar to carbon monoxide, thus blocking the mitochondrial respiration chain causing depletion of adenosine triphosphate. Hyperbaric oxygen (HBO2) is recommended for treating carbon monoxide poisoning. The therapeutic effect is due to a high oxygen pressure removing carbon monoxide from the cells. We hypothesise that HBO2 induces changes in whole-blood-cyanide by a competitive mechanism forcing cyanide out of cellular tissues. A rat model was developed to study this effect. Female Sprague Dawley rats were anesthetized with a fentanyl + fluanizone combination and midazolam given subcutaneously (s.c.). Rats were poisoned with 5.4 mg/kg KCN injected intra-peritoneally in Group 1 and intra-arterially in Group 2. Blood samples were taken immediately after poisoning, and at one and a half, three and five hours. Blood was drawn from a jugular vein in Group 1 and from a femoral artery in Group 2. Group 1 rats were divided into a control group of 12 rats without HBO2, 10 rats had acute HBO2 immediately after poisoning and a group of 10 rats had HBO2 one and a half hours after poisoning. Group 2 rats were divided into a control group and an acute HBO2 group, with 10 rats in both groups. Whole-blood-cyanide concentrations were measured using the Conway method based on diffusion and the subsequent formation of cyanocobalamin measured by a spectrophotometer. Results showed that whole-blood-cyanide concentration in Group 1 controls and acute HBO2 initially rose and then fell towards zero. In rats treated with delayed HBO2, the reduction in whole-blood-cyanide concentration was significantly less as compared to controls and acute HBO2-treated rats. Group 2 controls whole-blood-cyanide concentration decreased towards zero throughout the observation period. However, in Group 2 acute HBO2-treated rats a secondary rise in whole-blood-cyanide was observed. The study indicates that HBO2 can move cyanide from tissue to blood. These findings may be of clinical importance, as combined HBO2 and antidote treatment, may accelerate detoxification.

Iatrogenic systemic air embolism treated with hyperbaric oxygen therapy.

Air embolism is a rare and potentially severe complication of surgical and invasive procedures. Emboli large enough to produce symptoms require immediate treatment because of the risk of 'gas lock' in the right side of the heart and subsequent circulatory failure. If air is transmitted to the arterial circulation through a shunt, it may cause cerebral emboli with neurological symptoms. We present two cases with venous air emboli and concurrent cerebral arterial emboli. Both patients were successfully treated with hyperbaric oxygen therapy.

Immunoreactivity of bovine schwannomas.

Thirty schwannomas from 22 cows were examined immunohistochemically. All were positive for vimentin and Ki-67 but negative for pancytokeratin, neurofilament, and desmin. S-100 immunolabelling varied between and within lesions. The numbers of tumours giving positive results for S-100, neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) were 16, 30 and 25, respectively. It was concluded that vimentin-positive tumours suspected to be schwannomas should also be immunolabelled for NSE and GFAP to confirm the diagnosis.

Postural stability before and after hyperbaric oxygen treatment.

OBJECTIVE: The purpose of this study was to determine the effect of hyperbaric oxygenation (HBO) on postural stability in healthy volunteers. The study was performed in accordance with treatment protocols for divers' decompression sickness and carbon monoxide poisoning. METHODS: Twenty-one healthy male divers, aged 31 +/- 6.88 years (mean +/- SD), were tested with quantitative Romberg's test before and after HBO (90 min in a pressure chamber at an ambient pressure of 253 kPa, approximately 15 m of sea water, breathing pure oxygen). The quantitative Romberg's test is a calculation of the average sway for 50 s. RESULTS: No difference was found between sway before and after the HBO (P < 0.05), i.e. we were unable to show that the results of quantitative Romberg's test are affected by HBO. Thus, the quantitative Romberg's test may be a valuable tool in evaluating patients with decompressions sickness, carbon monoxide intoxication and other neurological diseases normally treated with HBO.

Diameter variations of retinal blood vessels during and after treatment with hyperbaric oxygen.

AIMS: To quantify retinal vascular change during and after hyperbaric oxygenation (HO) for 6x5 weekly 90 minute treatments. METHODS: Fundus photographs were taken before, during, and after HO at 2.5 atmospheres absolute pressure (ATA) on days 1, 2, 3, 10, 20, 29, and 30 of treatment on three patients using a specially developed hand held ophthalmoscope with a digital colour camera. Blood vessel diameter was estimated on red free retinal images. The mean of three measurements of arterioles and venoles close to the optic disc was calculated. Consistency and repeatability of the method was verified by estimating the diameter of the vessels by three measurements in each of seven images taken within 70 seconds on the same person. Analysis of variance with Bonferroni correction for multiple comparisons was conducted to ascertain whether significant intergroup differences existed. RESULTS: Breathing 100% oxygen at 2.5 ATA constricts retinal arterioles by 9.6% (standard deviation 0.3%) and venoles by 20.6% (SD 0.3%) of their size in air at ambient pressure. Constriction escalates during treatment. Ten minutes after the HO, arterioles dilate to 94.5% (SD 0.3%) and venoles to 89.0% (SD 0.3%) of their primary size. This pattern is the same for each day of measurement. Heart frequency falls continually during HO. Systolic, diastolic, and mean arterial pressures stay constant. CONCLUSION: Exposure to hyperbaric oxygen causes constriction of the retinal vessels. It is found that this constriction is constant through the series of treatments. This suggests that oxygen or products thereof are responsible for the vascular changes during and after hyperbaric oxygenation probably through autoregulation of the retinal vessels.

Biochemical markers for brain damage after carbon monoxide poisoning.

BACKGROUND: Carbon monoxide poisoning is associated with high mortality and a substantial risk for brain damage in survivors. Evidence for acute brain dysfunction may be obtained by measuring concentrations of suitable biochemical markers. We hypothesized that increased serum concentrations of Neuron-specific enolase (NSE) and S-100beta protein could be detected after carbon monoxide poisoning and that the concentration would correlate with the severity of intoxication. METHODS: Prospective non-interventional study in the university hospital. We included 20 patients admitted for hyperbaric treatment due to carbon monoxide poisoning. Serum levels of NSE and S-100beta protein were measured in all patients on admission and after 12, 24, 36 and 48 h. As a control group, we included 20 patients who underwent elective hyperbaric treatment. RESULTS: Serum concentrations of NSE and S-100beta protein were not significantly different from the controls, with median values at admission being 10.6 vs. 9.7 microg l(-1) and 0.15 vs. 0.13 microg l(-1), respectively (P = 0.82 and P = 0.38). The concentrations did not change significantly during the sampling period. We were unable to show any significant relation to level of consciousness. CONCLUSION: Blood concentrations of NSE and S-100beta protein were not significantly increased after carbon monoxide poisoning and do not seem to be related to a history of unconsciousness.

Isobutyl-nitrite-induced methemoglobinemia; treatment with an exchange blood transfusion during hyperbaric oxygenation.

A young man was accidentally intoxicated with isobutyl nitrite by a threefold lethal dose. Due to nitrites' ability to change hemoglobine into methemoglobine the patient showed signs of severe hypoxia, which could not be treated by conventional means. Therefore the patient was rapidly transferred to a hyperbaric chamber. The patient was treated with pure oxygen at 283 kPa under which a blood exchange transfusion was performed. The patient fully recovered.

Hyperbaric oxygen treatment and pulmonary function.

Hyperbaric oxygen (HBO2) treatment exposes the lungs to the potentially toxic effect of free oxygen radicals and may lead to impairment of pulmonary function. HBO2 significantly improves wound healing in patients with osteoradionecrosis of the mandible following radiation therapy for intraoral cancer. In 18 consecutive patients with osteoradionecrosis of the mandible, pulmonary function was assessed during 6 wk of HBO2 treatment, applied daily in a monoplace chamber for 90 min and at a partial oxygen pressure of 2.4 atm abs. Pretreatment forced vital capacity (FVC) was 104 +/- 14% (mean +/- SD) of a reference population, the 1 s forced expiratory volume (FEV1) 95 +/- 20%, total lung capacity (TLC) 100 +/- 13%, and the carbon monoxide diffusing capacity (DL(CO)) 81 +/- 17% (P < 0.05, compared to reference population). These parameters remained unchanged throughout the treatment period (after 6 wk and expressed relative to the percentage of the expected value at baseline): deltaFVC: +4 +/- 8%; deltaFEV1: -2 +/- 4%; deltaTLC: +2 +/- 5%; deltaDL(CO): 0 +/- 9%; deltaRV 0 +/- 11%. It is concluded that intermittent HBO2 treatment in a monoplace chamber has no persistent effect on pulmonary function and can be offered even to patients with a reduced diffusing capacity.

[Anesthesiologic aspects of multiorgan donation]. / Anaestesiologiske aspekter ved multiorgandonation.

As of July 1990 brain death was legally recognized in Denmark thereby rendering transplantation of heart, liver and lung possible. Brain death donors are usually treated in neurosurgical or anaesthetic intensive care units. The staff of these units influence the number of donors and also the quality of organs donated. Physiological factors pertinent to brain death donors and pre- and peroperative donor therapy in relation to multiorgan procurement are discussed from the viewpoint of the anaesthetist. Symptomatic therapy aimed at optimizing and maintaining organ function is employed; thus continuing intensive care. Sympathetic and somatic reflex responses to surgical stimulation are to be anticipated, often necessitating analgesics to blunt haemodynamic responses and neuromuscular blocking agents to inhibit movements and/or rigidity.

Postural stability during long-term treatment of cancer patients with epidural opioids.

Ten cancer patients treated with stable doses of epidural opioids were tested for postural stability. The postural stability was measured using a quantitative Romberg's test, performed on a computerized force-plate system. Sway tendencies in the sagittal and the transverse directions were recorded. The postural stability of the patients was compared with values obtained from healthy controls. Comparing the cancer patients with the controls, postural stability in eight out of ten patients was intact. The study suggests that long-term epidural opioid treatment has little influence on the patient's ability to stand safely.

Measurements of pressure on the sole of the foot in plaster of Paris casts on the lower leg.

Pressure on the sole of the foot inside three different types of plaster cast, used in treatment of fracture of the lower leg, was measured on six normal persons. No significant difference was found between these pressures in below-knee plaster, full length plaster including the thigh and patellar-tendon-bearing plaster. Only occasionally a relief in pressure was found in patellar-tendon-bearing plasters.

Postural stability by foot-to-ground force measurement.

The present study was made in an attempt to provide methods which by use of foot-to-ground forces were able to measure gait and postural stability parameters in a form apt for clinical use. The present study is based on 7 publications on the methods and results of gait analysis and 6 previously published studies on postural stability and one study using both methods. The present study is a more extensive description of the methods applied. The gait analysis is performed on an instrumented treadmill measuring continuous ground reaction forces for each foot separately. The advantage of the system is an extensive description of gait. The temporal factors, gait unsafety or ataxia is determined, and by the use of the Laws of Newton, the external positive and negative work is calculated for each foot. A material on normal gait has been published. Studies of gait describe improvement after a neurosurgical intervention as well as the influence of intake of alcohol on gait. The postural stability is measured by calculation of the average variations in the centre of the feet's pressure on a force plate. The advantage compared to previous studies is that one figure is considered a sufficient expression of the postural stability. A material of normal persons have been established and sequent studies have shown informative concerning the influence of various drugs and surgical interventions on the postural stability. The developed methods provide objective data permitting further basic studies. Applied studies should be done within the specialties of orthopedics, anaesthesia, neurosurgery, neurology and as part of search for effects and side-effects in pharmacology.

Gait analysis before and after osteotomy for hallux valgus.

Twenty-one female patients with bunions were treated by Mitchell osteotomy. Nineteen had clinically excellent or good results. This included no pain on walking, normal ambulation, and improved appearance. Two patients were dissatisfied. By using an instrumented treadmill the gait function was tested before and a median of 6 1/2 months after operation. No significant improvements or losses were found in a large series of gait parameters. The benefits of operation were not due to an improved gait function and other factors must have influenced the final result.