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Biomedical subjects

R Houston

Publications and source records attributed to R Houston.

At least 37 records · Page 2Linked to original sources
PubMed1991

Non-invasive in vivo near-infrared optical measurement of the penetration depth in the neonatal head.

The non-invasive optical technique of near-infrared spectroscopy (NIRS) was used to measure the depths of light penetration at four wavelengths in the NIR region. Near-infrared absorbance measurements were carried out on 10 preterm infants. The apparent absorbance data (in optical density units) collected at 775, 805, 845, and 904 nm were measured at different positions on the head. Linear relationships that satisfy the Lambert law were obtained when the apparent absorbance at a given wavelength was plotted against the inter-optrode distance. From the slopes of the resulting straight lines, the depth of penetration of the NIR light was calculated and found to be independent of the position of the probes on the head. Calculated average values of the depth of penetration of near-infrared light in the whole neonatal head ranged between 6.3 and 8.5 mm.

Head↗
PubMed1990

The effect of oral and parenteral typhoid vaccination on the rate of infection with Salmonella typhi and Salmonella paratyphi A among foreigners in Nepal.

We studied the incidence of enteric fever among travelers and foreign residents who attended an expatriate clinic in Kathmandu, Nepal, from February 1987 to June 1988. There were 42 cases of enteric fever; 20 were caused by Salmonella typhi and 22 by Salmonella paratyphi A. Among 18 unvaccinated foreigners who had enteric fever, S typhi was isolated from 67%, and S paratyphi A from 33%, a ratio similar to the local Nepalese population. Among 22 vaccinated foreigners, S typhi was isolated from 35%, compared with 65% with S paratyphi A. Nine percent of tourists had received the oral Ty21A typhoid vaccine. However, among seven vaccinated tourists who became infected with S typhi, four (57%) had received the oral vaccine. Typhoid vaccine efficacy for tourists was calculated and showed an overall protective rate of 90% against enteric fever in general, 95% protection against S typhi, and 72% to 75% protection against S paratyphi A. We conclude that typhoid vaccine should be recommended to all travelers to the Indian subcontinent, and since S paratyphi A is the predominant cause of enteric fever among vaccinated travelers, consideration should be given to an effective vaccine against S paratyphi A when that becomes available.

Administration, Oral↗
PubMed1989

Helicopter rescues and deaths among trekkers in Nepal.

Trekking in Nepal is a popular recreational activity that involves approximately 45,000 persons each year. The health risk of trekking in Nepal has never been calculated. We retrospectively studied all helicopter evacuations and deaths among trekkers in Nepal between Jan 1, 1984, and June 30, 1987. A total of 148,000 persons obtained trekking permits during that time. Twenty-three persons died and 111 were rescued by helicopter. The risk of dying while trekking was 15 deaths per 100,000 trekking permits. The frequency of helicopter rescue was 75 per 100,000 trekking permits. The most frequent cause of death was trauma (11 persons), followed by illness (eight persons) and acute mountain sickness (three persons). Deaths occurred equally at all altitudes from 1000 m to over 5000 m, although the number of persons at risk at different altitudes could not be calculated. These data suggest that trekking in Nepal is a relatively safe activity, but a decision to embark on a trek in Nepal should be individualized, with an understanding of the problems related to remoteness, altitude, and illness in the absence of medical facilities.

Adolescent↗
PubMed1988

Etiology of diarrhea among travelers and foreign residents in Nepal.

A bacterial pathogen was isolated from 47% of 328 expatriate patients with diarrhea seen at two medical clinics in Nepal in 1986. Enterotoxigenic Escherichia coli (24%), Shigella (14%), and Campylobacter species (9%) were isolated most frequently. Enteroinvasive and adherence factor-positive E coli were isolated from 2% and 1% of patients, respectively. Giardia lamblia was detected in 12% of patients, rotavirus in 8%, and Cryptosporidium and Entamoeba histolytica each in 5%. Blastocystis hominis was present in 33% of patients but in only 9% of those who took trimethoprim-sulfamethoxazole. More than one enteropathogen was detected in 17% of patients. Patients with prolonged symptoms (longer than two weeks) were more likely to have Giardia (27%) and less likely to have Shigella (5%) than were patients with acute symptoms. The isolation rates of bacterial pathogens decreased with length of stay in Nepal. A wide variety of enteropathogens were detected in travelers to Nepal, and Shigella and protozoa were particularly important. Length of time abroad and duration of symptoms were important diagnostic considerations.

Adult↗
PubMed1986

Cost containment and increasing competition: implications for the PA profession.

Current trends in cost containment and increasing competition present opportunities--as well as challenges--to the PA profession. In this synopsis of an APAP workshop, the moderators present the views of the PA educators who explore this topic. Discussion focuses on opportunities and challenges, the attitude of the general public and various industry professionals (including physicians) toward increased utilization of PAs, and additional competition to the PA profession from other nonphysician health care providers. Strategies for addressing these issues are included.

Economic Competition↗
PubMed1979

Pain in patients with spinal cord injury.

For this study of intractable pain after spinal cord injury (SCI), a questionnaire was developed, pilot-tested and mailed to 356 previously hospitalized SCI patients, 200 (56%) of whom returned the completed questionnaire. Of the respondents, 160 (80%) reported abnormal sensation and 96 (48%) called the discomfort painful. Abnormal sensations were first noted within 6 months of injury by 105 patients, from 7 months to 4 years after injury by 39, and longer than 4 years after injury or unknown by 16. Pain locations varied and were unrelated to the level of lesion. In 30% of those reporting abnormal sensation the location of pain remained stationary, whereas in 17% it changed over time. The intensity of pain was described as severe to extreme by 25%; 44% indicated that it interfered with daily activities. Increase of pain over time was noted by 41%. Activity, inactivity, weather change and overexertion were not frequently identified as aggravating circumstances. Rest and medication were cited as alleviating factors. Approximately 38% of those experiencing pain used medications but only 22% obtained consistent relief from their use. Patients with low level lesions were more willing to exchange a hypothetical chance of recovery and/or loss of reacquired physiologic functions for pain relief than were patients with higher lesions.

Activities of Daily Living↗
PubMedDate not supplied

Fetal and neonatal cerebral oxygen monitoring with NIRS: theory and practice.

Near infra-red spectroscopy (NIRS) is a comparatively new method for monitoring the oxygenation in blood and tissue in the brain of the fetus and the neonate. Absorption of light in the wavelength range 700-1000 nm through such tissue is measured, which is then used to calculate changes in the concentration of cerebral oxygenated and de-oxygenated haemoglobin (HbO2 and Hb) and hence cerebral blood volume (CBV). Studies carried out on several groups of newborn babies have shown clear changes in HbO, Hb and CBV with hypoxia and bradycardia. These changes may well have implications in the occurrence of hypoxic/ischaemic brain injury. Intra partum NIR measurements on the fetal brain have demonstrated clear changes in HbO2, Hb and CBVm, coinciding with the onset of contractions.

Brain↗
PubMedDate not supplied

Short report: documentation of iodine deficiency in Haitian schoolchildren: implication for lymphatic filariasis elimination in Haiti.

In this study we documented unexpected moderate-to-severe iodine deficiency in Haitian schoolchildren although they live in a coastal community where presumably they have access to iodine-containing seafood. This fact combined with the lack of an iodized salt supply and endemic lymphatic filariasis makes community distribution of diethylcarbamazine-fortified, iodized salt an attractive strategy for elimination of lymphatic filariasis and iodine deficiency disorders in this area of Haiti. Combining lymphatic filariasis elimination with other public health interventions is one strategy to increase its public health benefit and maximize the impact of limited public health resources.

Child↗