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Biomedical subjects

M K Yousef

Publications and source records attributed to M K Yousef.

At least 19 recordsLinked to original sources
PubMed2001

Differentiated thyroid carcinoma referred for radioiodine therapy.

OBJECTIVE: The current work was conducted to study the disease status and treatment results of patients with differentiated thyroid carcinoma referred for radioactive iodine therapy. METHODS: Retrospective review of 78 patients with differentiated thyroid carcinoma referred for radioiodine therapy in the Nuclear Medicine Unit, King Abdulaziz Hospital and Oncology Center, Jeddah, Kingdom of Saudi Arabia. Analysis of the clinicopathologic characteristics, age correlation to different risk factors, treatment protocol and results were performed. RESULTS: Seventy seven percent were female and the female to male ratio was 3.5:1. The age of patients ranged between 13-63 years with a median age of 36 years. Cervical lymph node involvement was detected in 22 patients (25%). Papillary carcinoma was encountered in 78 patients (90%) and follicular carcinoma in 9 patients (10%). Analysis of the clinicopathologic characteristics showed no statistically significant difference between patients in the different age groups except for extrathyroid extension and lymph node involvement. Patients older than 45 years had a statistically significant lower incidence of nodal involvement and higher incidence of extra thyroid extension (P<0.02). In the current study we used a high dose method (Radioiodine-131 dose 75-100mCi) for thyroid remnant ablation after thyroidectomy (total or near total) in 67 patients. An Iodine 131 dose of 150 mCi was used in 12 patients with radioiodine-avid cervical lymph nodes and in 3 patients with gross residual tumor. In 4 patients with distant metastases an Iodine 131 dose of 200 mCi was used. For the whole study group the 5 year overall survival and disease-free survival was 96% and 88%. CONCLUSION: The current study, as with many other retrospective studies, concluded that despite the fact that differentiated thyroid carcinoma is among the most curable cancers, some patients are still at high risk for recurrent disease and associated mortality.

Adolescent↗
PubMed2001

Neuroblastoma.

OBJECTIVE: Due to the poor results achieved on combination chemotherapy and the unproven cost-effectiveness value of myeloablative therapy, the question has been raised; should patients with stage IV neuroblastoma be actively treated? The aim of the current study is to analyze retrospectively treatment results of 43 children with neuroblastoma with special stress on the rate and duration of remission in children with disseminated neuroblastoma. METHODS: Treatment of children with neuroblastoma consisted of surgical removal of the tumor, if possible, followed by chemotherapy for unresectable residual tumor including metastases. Second look surgery was performed to resect residual masses rendered resectable on chemotherapy in the absence of distal metastases. The chemotherapy protocol used in the current study consisted of alternating combination chemotherapy regimens containing, Cyclophosphamide, Vincristine and Doxorubicin, alternating with Cis-platinum and Etoposide. RESULTS: The male to female ratio was 2:1 with a median age of 2.1 years. The abdomen was the primary site of involvement encountered in 32 patients (74%). According to the childrens cancer study group (CCSG) staging system, only 6 patients (14%) had localized tumors (stages I and II). Two patients (5%) were found to have stage IV. Stage III was documented in 5 patients (12%). The majority of patients (70%) had disseminated disease at presentation. The bone marrow was the most common site of metastatic deposit, encountered in 23 patients out of the 30 with stage IV disease (77%). Out of the 12 evaluable non-stage IV patients, only one patient (8%) showed treatment failure. Assessment of response by the end of the 6th month from the date of diagnosis revealed that out of the 27 evaluable patients with stage IV, 4 patients achieved complete remission, 7 patients achieved very good partial remission, 8 patients achieved partial remission and 4 patients achieved mixed response. Three patients showed progressive disease on chemotherapy. Twenty-one patients (78%) were symptom-free and were conducting normal life. Assessment of response to treatment by the end of the 12th month from diagnosis revealed that 6 patients (2 complete remissions, 1 very good partial response, 3 partial responses) were maintaining their remission. Out of the 19 patients showing complete or partial remission at early assessment, 4 patients maintained their remission for more than 18 months. Two (one was in complete remission and the other was in partial response) of them progressed in areas of previous involvement after 20 and 21 months. The other 2 patients (one was in complete remission and the other was in partial response) showed disease progression in areas not previously affected by disease at presentation after 23 and 42 months. CONCLUSION: Results of treatment by multiagent chemotherapy regimens used in the current study show that children with neuroblastoma, even those with advanced stages, should receive the benefit of intensive multimodal therapy, even those with partial response to initial therapy. These patients may experience reasonable symptom-free and sometimes, disease-free survival.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Biometeorology and animal protein production: the case of arid lands.

To meet the food demands of the ever-increasing world population, man's only major future land bank is the arid lands. However, their exploitation has been limited and constitutes a major challenge to many scientific disciplines. Under the present conditions of hunger and/or malnutrition, a large-scale expansion in food production is not to be expected. Hence, it is imperative that in any development programme for arid lands, malnutrition, in general, and a deficiency of animal proteins, in particular, should be considered. Major advancements have been made, but much remains to be learned and implemented. Improvement of native farm animals should be the first step in increasing the availability of animal proteins. This may be achieved by an educational programme to enhance management, housing, food intake, etc. Then a breeding programme selecting for high productivity can be pursued. After eliciting the maximum return from the present livestock, attention should be directed to domesticating wild ungulates and/or introducing highly productive temperature-zone breeds for upgrading the local animals. Additionally, new potential and unconventional sources of animal proteins must be explored. Aquaculture, in particular, has the potential of producing large quantities of lower-cost protein-rich food. Available evidence in arid regions of the developed countries, i.e. USA and Australia, promises favourable results in our efforts toward increasing the production of animal protein. By innovative methods and long-term planning, such successes can be adapted and transferred to other regions of the world, with the aim of gradually lessening the present state of malnutrition and hunger.

Animal Husbandry↗
PubMed1989

Thermoregulatory responses of diabetic rats.

1. Thermal responses and skin microcirculation were measured in streptozotocin-induced diabetic (SD) rats during acute and chronic exposure to ambient (Ta) temperatures ranging from about 5 to 35 degrees C. 2. At 28 degrees C, SD rats had higher rate of oxygen consumptions (VO2), tail skin blood flow (SKBF), but lower rectal temperatures (Tre) than saline-injected controls. 3. Chronic exposure of the SD rats to 35 and 5 degrees C caused a sharp rise and decline in Tre, respectively. 4. At 35 degrees C, hyperthermia in the SD rats was associated with greater increase in VO2 than controls, but changes in SKBF were similar in both groups. 5. At 5 degrees C, VO2 changed similarly in both the SD and control rats, but vasoconstriction was greater in the controls. 6. The data suggest that hypothermia in SD rats may be associated with impairment of vasoconstriction and hyperthermia may be related to an increase VO2 not accompanied by greater vasodilation.

Animals↗
PubMed1988

Sweating and cardiovascular responses of aged men to heat exposure.

In this study, 6 older and 10 younger Japanese men were exposed, while sitting, to 40 degrees C and 40% relative humidity for up to 130 min. All participants were heat unacclimatized. Physiological measurements included sweat responses, esophageal and skin temperatures, nonevaporative heat exchange, heart rate, cardiac output, blood pressure, forearm blood flow, and metabolic heat production. There was no significant difference in sweat rate or in onset of sweating between the older and younger men; however, esophageal temperature at the onset of sweating was greater in the older men. Changes in skin temperature, nonevaporative heat exchange, metabolic heat production, heart rate, and cardiac output were the same during heat exposure in both age groups. However, forearm blood flow before and after exposure to heat was significantly lower in the elderly group. These data suggest that the greater health risk posed to resting, yet healthy, aged men by hot environments is not a consequence of inadequate sweating but could be associated with retardation of the vasodilation reflex, which can prevent effective transfer of the body heat to its shell, thus resulting in greater heat storage.

Adult↗
PubMed1988

Water temperature and intensity of exercise in maintenance of thermal equilibrium.

This study examined the thermal and metabolic responses of six men during exercise in water at critical temperature (Tcw, 31.2 +/- 0.5 degrees C), below Tcw (BTcw, 28.8 +/- 0.6 degrees C), at thermoneutrality (Ttn, 34 degrees C), and above Ttn (ATtn, 36 degrees C). At each water temperature (Tw) male volunteers wearing only swimming trunks completed four 1-h experiments while immersed up to the neck. During one experiment, subjects remained at rest (R), and the other three performed leg exercise (LE) at three different intensities (LE-1, 2 MET; LE-2, 3 MET; LE-3, 4 MET). In water warmer than Tcw, there was no difference in metabolic rate (M) during R. The M for each work load was independent of Tw. Esophageal temperature (Tes) remained unchanged during R in water of ATtn (36 degrees C). However, Tes significantly (P less than 0.05) declined over 1 h during R at Ttn (delta Tes = -0.39 degrees C), Tcw (delta Tes = -0.54 degrees C), and BTcw (delta Tes = -0.61 degrees C). All levels of underwater exercise elevated Tes and M compared with R at all Tw. In water colder than Tcw, the ratio of heat loss from limbs compared with the trunk became greater as LE intensity increased, indicating a preferential increase in heat loss from the limbs in cool water. Tissue insulation (Itissue) was lower during LE than at R and was inversely proportional to the increase in LE intensity. A linearly inverse relationship was established between Tw and M in maintaining thermal equilibrium.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Physiological responses of aged men to head-up tilt during heat exposure.

The effects of age on cardiovascular and thermoregulatory responses to passive tilting were investigated using six old (61-73 yr) and 10 young (21-39 yr) unacclimatized men. Experiments were carried out at 26 degrees C and after exposure to 40 degrees C and 40% relative humidity for 105 min. Continuous measurements of esophageal (Tes) and mean skin (Tsk) temperatures and heart rate (HR) were recorded. Other variables studied included blood pressure (BP), forearm blood flow (FBF), and cardiac output (CO), which were measured at 4- to 5-min intervals. Measurements were made in the supine position and after 70 degrees head-up tilt for 15 min. Cardioacceleration during the tilt test was greater in the young men than in the old. Other cardiovascular responses of the old men to orthostatism were qualitatively similar to that of the young except for FBF and forearm vascular conductance. The old men did not show significant changes in FBF during tilting, suggesting a deterioration in the sympathetic nervous reflex in the aged. However, other circulatory adaptations seemed to overcome this deficiency resulting in orthostatic tolerance similar to that of the young. During head-up tilt at 26 and 40 degrees C, Tes of both age groups increased. This may reflect a decrease in conductive heat transfer presumably due to diminished blood flow to the periphery.

Aged↗
PubMed1986

Heat stress: a threat to health and safety.

This review offers a rational basis for the use of fundamental physiological controlling mechanisms in setting safe environmental limits for occupational situations where heat stress is encountered. There is no single index of heat stress that has been universally accepted. However, the use of wet bulb glove temperature (WBGT) has been adopted by various organizations on occupational health and safety in several industrial countries. Thermal limits suggested for everyday work continue to be subject to argument. The controversies arise from the fact that many factors such as individual variations, acclimatization, clothing, age, sex, physical fitness and work load lead to significant effects on tolerance of man to heat. Several measures for prevention of heat stress under industrial situations are summarized briefly. There is no agreement on a single measure to be used, rather a combination of these measures can be the most effective mean to alleviate or prevent severe heat stress. It is to be hoped that this review may help public health officials and medical doctors of various work occupations resolve some of the problems that arise in setting thermal limits and preventive measures, thus contributing to increase productivity and efficiency of work.

Acclimatization↗
PubMed1986

Thermoregulatory responses of the elderly population.

With a significant rise in the elderly population of the developed industrialized countries due to increased life span the harmful consequences of heat and cold stresses are expected to be more notable. Although effects of these harmful stresses on morbidity and mortality of the elder population are well documented in medical reports, relatively few studies are notable for the investigation of age-related effects on thermoregulation. In this report, data on responses of older individuals to heat stress during rest and exercise are summarized. When old men (60-86 years) were exposed to 40 degrees C and 40% relative humidity for 2 hr during rest, their total body sweat rate/m2 (SR) was similar to the young group (20-35 years). The onset of sweating was also similar in both groups. Regional SR was not uniform in either age group. Since the responses of both groups were similar, data were pooled to examine the relationship between age and physical fitness, as measured by aerobic capacity (VO2 max), to physiological responses. Only VO2 max and body fat were significantly related to age. The SR was related to fitness. When old men and women walked at a level costing 40% of their VO2 max in desert heat for 1 hr, total SR was similar in all age groups. The efficiency of walking was similar in young and old, but the least fit individuals were less efficient. In all our studies, the data clearly indicate that age per se does not decrease the functional capacity of the sweating mechanism and that problems encountered by the elderly in hot environments are primarily related to impairment of the cardiovascular functions.

Age Factors↗
PubMed1986

Central metabolism of beta-endorphin in different species of temperature acclimated rodents.

The purpose of this study was to characterize the central metabolism/processing of beta-endorphin in wild, desert rodents and to study the effect of heat and cold acclimation on central metabolism/processing and beta-endorphin half-life. This report suggests that a shift occurs in the processing of beta-endorphin in desert rodents acclimated to heat and cold leading to an accumulation of gamma-type endorphins. The data support a significant difference in beta-endorphin half-life between the rodents and the laboratory white rat.

Acclimatization↗
PubMed1984

Thermoregulatory responses to desert heat: age, race and sex.

Sixty-nine whites (38 men and 31 women) aged 17 to 88 years and 48 blacks (19 men and 29 women) aged 17 to 61 years were studied. Each person walked in desert heat for 1 hour at a rate requiring 40% of aerobic capacity. Observations were recorded on their rectal temperature (Tre), skin temperature (Tsk), heart rate (HR), blood pressure, and sweat rate (SR). Older men and women of both races were able to complete their walks without any ill effects. Age, per se, did not significantly reduce elderly individuals' ability to tolerate the combined stress of dry heat and exercise. Men of both races had higher sweat rate and lower heart rate and rectal and skin temperature than women working at the same percentage of aerobic capacity. Success of thermoregulation at 40% of aerobic capacity of blacks and whites was equal, but in both races men thermoregulated more successful than women. Our data suggest that thermoregulatory capacity of humans under desert conditions differs between sexes and is not influenced significantly by age or race except for differences in aerobic capacity.

Adolescent↗
PubMed1983

Volume and composition of hand sweat of White and Black men and women in desert walks.

Many investigators have sought, but failed to find, ethnic differences in the number and regional distribution of active sweat glands. In this study measurements have been made of sweat secreted on one hand and also on the whole body of Whites and Blacks walking in desert heat. Whites numbered 31 men and 27 women, ages 30 to 88 years; there were 21 Black men and 31 Black women, ages 16 to 61 years. Each walked on three occasions for 1 hour at a rate that required an oxygen consumption of about 40% of aerobic capacity. Ambient temperature ranged from 32 to 44 degrees C in 1979 and 1980; means were 38.4 degrees C in 1979 and 36.7 degrees C in 1980. There was no sweat in the gloves of many Blacks; this was true of only a few Whites. Volume of body sweat increased in both races with rate of walking; volume of hand sweat increased more in Whites than in Blacks. The Mann-Whitney test revealed that volumes of hand sweat were significantly greater for Whites than for Blacks. It was concluded that in desert walks most Whites and few Blacks sweat freely on their hands. In samples of hand sweat, Na+, K+, and Cl- were determined. Concentrations of each ion varied widely in both races, and were unrelated to race. Concentrations of Na+ and Cl- generally are somewhat higher in hand sweat than in body sweat; concentrations of K+ are much higher. It follows that the values for concentration of Na+ and Cl- reported in Table 3 probably are somewhat higher than would have been found in body sweat, and concentrations of K+ are probably much higher.

Adult↗
PubMed1982

Metabolic observations on Caucasian men and women aged 17 to 88 years.

Aerobic capacity (VO2 max) and body fat were measured indoors and VO2 was measured at about 36 to 42 degrees C in desert walks or runs in 69 adults aged 17 to 88 years. Eleven were athletic youths, and many of the older adults had participated in jogging programs. Body fat increased and VO2 max decreased with age, although there were notable exceptions. Rates of walking and running were planned to require about 40% of VO2 max. Midway in each walk VO2 (ml O2/horizontal m . kg) served as a measure of skill; skill was high in 10 of 11 youths who did many walks or runs. Each older adult did three walks; skill improved. In four groups with some persons aged 50 and older with body fat up to 40%, skill in their third walk matched that of youths. The least fit women and the least fit men did not attain that level of skill.

Adipose Tissue↗