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Biomedical subjects

R Yip

Publications and source records attributed to R Yip.

At least 73 records · Page 4Linked to original sources
PubMed1993

Lack of importance of the superior laryngeal nerves in citric acid cough in humans.

The relative importance of laryngeal afferents in the cough reflex in humans is unknown. This study was designed to investigate the importance of superior laryngeal nerve afferents in the cough reflex induced by inhaled nebulized citric acid in awake humans. Nine healthy volunteers had their cough thresholds to inhaled nebulized citric acid measured after superior laryngeal nerve conduction blockade and after a sham nerve block. Of the nine subjects, four showed no change in cough threshold after superior laryngeal nerve anesthesia, three showed increased cough threshold after nerve block compared with no block, and two showed decreased cough threshold after nerve block. The geometric means of the cough thresholds for the nerve block vs. sham block tests were 16 +/- 13 (SD) and 15 +/- 8% citric acid, respectively. There was no statistically significant difference (Wilcoxon signed-rank test) between the cough thresholds with and without superior laryngeal nerve block (P > 0.05). We conclude that, in the awake human, superior laryngeal nerve afferents do not play a necessary role in initiation of citric acid-induced cough.

Administration, Inhalation↗
PubMed1993

The lack of effect of routine magnesium administration on respiratory function in mechanically ventilated patients.

STUDY OBJECTIVE: We wished to determine if magnesium infusion would improve respiratory muscle function in long-term ventilated patients even in the absence of hypomagnesemia. DESIGN: Prospective study of mechanically ventilated patients using a double-blind crossover design. SETTING: A combined medical-surgical ICU of a university teaching hospital. PATIENTS: Twenty-one separate admissions to the ICU in 20 patients were studied. Patients who were selected had been intubated and mechanically ventilated for at least 6 days with the admitting diagnosis of respiratory failure. INTERVENTIONS: Twelve patients received 6 g MgSO4 intravenous (i.v.) infusion over 16 h on day 1 followed by placebo infusion on day 2. Nine patients received placebo on day 1 followed by MgSO4 (6 g i.v.) on day 2. MEASUREMENTS AND MAIN RESULTS: We measured vital capacity (VC), maximal inspiratory pressure (Pmax) and maximal expiratory pressure (Pemax) in all patients. There were no significant differences in Pimax (37 +/- 14 vs 42 +/- 20 cm H2O), Pemax (59 +/- 32 vs 61 +/- 38 cm H2O), and VC (850 +/- 460 vs 960 +/- 490 ml) comparing values before and after magnesium infusion. We could not find a subgroup of patients with a marked improvement in Pimax or Pemax. CONCLUSIONS: In patients requiring mechanical ventilation for respiratory failure, magnesium infusion is not associated with increased respiratory muscle strength. Although a trial of MgSO4 administration may be considered for patients with difficulty weaning from mechanical ventilation, it is unlikely to result in clinical improvement.

Adult↗
PubMed1992

Pediatric nutrition surveillance system--United States, 1980-1991.

The CDC Pediatric Nutrition Surveillance System (PedNSS) monitors the general health and nutritional characteristics of low-income U.S. children who participate in multiple public health programs. This system is intended to characterize trends and patterns in key indicators of nutritional status so that the information can be used for program planning and targeting. The indicators monitored by PedNSS are birth weight, childhood growth status, anemia, and breast-feeding patterns. From 1980 through 1991, the trends for low birth weight, low height-for-age (shortness), low weight-for-height (thinness), and high weight-for-height (overweight) were stable for all children monitored by the PedNSS, with the exception of Asian children, who were predominantly of Southeast Asian refugee background. In the early 1980s, the prevalence of low birth weight and shortness was higher among Asian children than among children of other racial or ethnic groups who were monitored by the PedNSS. However, these prevalences declined steadily from 1980 through 1991. By 1991, the prevalences of low birth weight and shortness for Asian children were similar to those observed for children of other races/ethnic groups. Overall, low-income U.S. children had a slightly lower height-for-age than expected, indicating that some of these children were at a health and nutritional disadvantage. The prevalence of overweight varied among different racial/ethnic groups; Hispanic and Native American children had the highest prevalences of overweight. The 20%-30% prevalence of anemia among low-income children monitored by the PedNSS was higher than among the general population, reflecting in part the preferential enrollment and retention of anemic children by public health nutrition programs and also indicating that many children had inadequate iron nutrition. From 1980 through 1991, the prevalence of anemia declined > 5% for most of the age- and race/ethnicity-specific groups monitored by PedNSS. That decline represents an improvement in iron nutritional status. PedNSS is a useful system for the monitoring and characterization of the nutrition status of low-income children at both state and national levels.

Adolescent↗
PubMed1992

Pregnancy nutrition surveillance system--United States, 1979-1990.

Since 1979, the CDC Pregnancy Nutrition Surveillance System (PNSS) has monitored behavior and nutritional risk factors among low-income pregnant women participating in public health programs. Although the states contributing to the system have varied over the period, the PNSS is able to characterize the behavior and health outcomes of pregnant women from diverse low-income populations. In 1990, 66.2% of the women in the system initiated prenatal care during the first trimester of pregnancy; 26.4% smoked during pregnancy. Since 1979, the prevalence of smoking remained relatively stable for white women, but declined for blacks and Hispanics. Prepregnancy body mass index (BMI, defined as kg/m2) showed marked changes from 1979 through 1990; the prevalence of underweight (BMI < 19.8) declined steadily and the prevalence of overweight (BMI > 26) increased steadily. In 1990, 39.3% of the women had gestational weight gains below levels recommended by the National Academy of Sciences. Both prepregnancy underweight and inadequate gestational weight gain were associated with greater risk for low birth weight in the PNSS. The prevalence of anemia at each trimester has remained stable since 1979. In 1990, 9.8%, 13.8%, and 33% of the women reported by the PNSS were anemic in the first, second, and third trimesters, respectively. Anemia in the first trimester appeared to be strongly associated with a high risk of low birth weight; this association was attenuated in later trimesters. These findings indicate the need to improve iron nutrition among low-income women.

Adolescent↗
PubMed1992

The relation of prothrombin times to coronary heart disease risk factors among men aged 31-45 years.

Although levels of coagulation factor VII and fibrinogen are predictive of cardiovascular disease, relatively little data describe hemostatic characteristics in healthy populations. The cross-sectional associations between the prothrombin time, a measure of the activity of the extrinsic and common pathways of coagulation, and traits associated with the risk of cardiovascular disease were therefore examined among 3,604 white and 514 black, male, US Army veterans aged 31-45 years. The prothrombin time measurements, performed in 1985 and 1986, were precise, with an intraclass correlation of 0.98 (202 pairs). Overall, the mean prothrombin time was 12.4 seconds (standard deviation, 0.4 seconds), and 11 percent of the men had a value of less than 12 seconds. Many of the observed associations with the prothrombin time paralleled those that have been reported with clotting factor VII and fibrinogen. The mean prothrombin time was 0.15 seconds shorter among whites than among blacks and was 0.2 seconds shorter among current cigarette smokers than among men who had never smoked. Inverse associations were also seen with relative weight and with levels of total cholesterol and triglycerides (r = -0.09 to -0.16). All associations were statistically significant at the 0.01 level, and the examined characteristics could jointly account for about 12 percent of the variability in prothrombin times. Additional data on characteristics related to coagulation may help elucidate the natural history of cardiovascular disease and aid in the design of clinical trials.

Adult↗
PubMed1992

Improving growth status of Asian refugee children in the United States.

OBJECTIVE: To analyze the trend and pattern of the nutrition status of Southeast Asian refugee children and other low-income children in the United States. DESIGN: Descriptive analysis of the growth data from the Pediatric Nutrition Surveillance System of the Centers for Disease Control, Atlanta, Ga, from 1980 through 1989. SUBJECTS: Children under 5 years of age from low-income families enrolled in public health clinics in 12 selected states. MEASUREMENTS AND MAIN RESULTS: Asian refugee children experienced a progressive and significant decline in the prevalence of low birth weight, low height-for-age, and low weight-for-age, while these nutritional indexes remained stable for low-income white, black, and Hispanic children. By 1989, the growth status of Asian children was near that of other ethnic groups. CONCLUSIONS: The marked improvement of growth status among Asian refugee children over a short period suggests that the poor growth status often observed among recently immigrated Asian children is primarily related to nutritional and health factors, rather than genetic factors. In assessing the growth of Asian or immigrant children, it would be helpful to take their family and early childhood background into account.

Black or African American↗
PubMed1992

Gastroesophageal reflux during anaesthesia.

While the number of patients at risk for vomiting and aspiration has been reported to be high, the incidence of clinically important pulmonary aspiration is low. We sought to define the incidence of gastroesophageal reflux (GER) and to correlate this with the clinical variables of obesity, history of oesophagitis, bucking and changes in body position. Continuous oesophageal pH measurement was used to determine the frequency of gastroesophageal reflux in 44 patients having general anaesthesia for elective surgical procedures. Acid reflux to a pH value of less than four occurred in seven patients (15.9%) during anaesthesia. This was associated temporally with straining on the endotracheal tube in six subjects (13.6%). We conclude that traditional risk factors are not always predictive of those patients at risk of regurgitation and aspiration.

Abdomen↗
PubMed1992

Iron nutrition does not account for the hemoglobin differences between blacks and whites.

Many researchers have reported lower hemoglobin concentrations in blacks than in whites, but the reason for this difference is unknown. Data for 2515 persons (in 3-12 y and 18-45 y age groups) from the Second National Health and Nutrition Examination Survey (NHANES II) were evaluated to investigate the roles of iron intake and biochemical iron status indicators in explaining black and white differences in hemoglobin concentration. Dietary iron intake was estimated from one 24-h food recall, and hemoglobin, serum ferritin, transferrin saturation and erythrocyte protoporphyrin were measured by standard laboratory methods. Hemoglobin levels were substantially lower in black children (120.3 g/L) than in white children (126.8 g/L). Hemoglobin concentrations were also lower in black women (128.4 g/L) than in white women (133.9 g/L), and in black men (144.8 g/L) than in white men (153.2 g/L). Blacks had lower hemoglobin concentration than whites at most levels of dietary iron intake, serum ferritin, transferrin saturation and erythrocyte protoporphyrin. Despite their lower hemoglobin levels, blacks had higher serum ferritin levels than whites. These results suggest that the difference in hemoglobin concentrations between blacks and whites in the United States is the result of factors other than iron intake and iron status. More specific investigations of both the genetic and environmental determinants of iron utilization in blacks are needed.

Adult↗
PubMed1992

Postoperative respiratory function after laparoscopic cholecystectomy.

Open cholecystectomy causes changes in pulmonary function test volumes; such changes can be related to respiratory complications of hypoxemia and atelectasis. Little data is available on lung volume changes after laparoscopic cholecystectomy. We measured preoperative and postoperative vital capacity (VC), functional residual capacity (FRC), arterial PO2, and chest X-ray atelectasis in 31 patients undergoing laparoscopic cholecystectomy and found small but significant decreases (p < 0.01) in VC (13 +/- 19%) and FRC (7 +/- 17%). The PO2 decreased from 89 +/- 11 mm Hg to 82 +/- 14 mm Hg, with only one patient's PO2 less than 60 mm Hg. Three patients demonstrated new segmental lobar collapse on postoperative chest X-ray. The postoperative changes in FRC (R2 = 0.40, p < 0.04) and atelectasis (R2 = 0.46, p < 0.03) could be predicted by multiple regression of risk factors, including obesity, smoking, use of narcotics, age, and symptoms of prior respiratory disease. We conclude that the respiratory changes after laparoscopic surgery are small in comparison to those expected after open cholecystectomy.

Cholecystectomy, Laparoscopic↗
PubMed1991

Iron status with different infant feeding regimens: relevance to screening and prevention of iron deficiency.

The objective of this study was to evaluate the benefit of screening for anemia in infants in relation to their previous diet. The iron status of 854 nine-month-old infants on three different feeding regimens and on a regimen including iron dextran injection was determined by analysis of hemoglobin, serum ferritin, and erythrocyte protoporphyrin levels and of serum transferrin saturation. Infants were categorized as having iron deficiency if two or three of the three biochemical test results were abnormal and as having iron deficiency anemia if, in addition, the hemoglobin level was less than 110 gm/L. The prevalence of iron deficiency was highest in infants fed cow milk formula without added iron (37.5%), intermediate in the group fed human milk (26.5%), much lower in those fed cow milk formula with added iron (8.0%), and virtually absent in those injected with iron dextran (1.3%). The corresponding values for iron deficiency anemia were 20.2%, 14.7%, 0.6%, and 0%, respectively. The use of iron supplements is therefore justified in infants fed cow milk formula without added iron, even when there is no biochemical evidence of iron deficiency. The low prevalence of iron deficiency in the group fed iron-fortified formula appears to make it unnecessary to screen routinely for anemia in such infants. These results also support the recommendation that infants who are exclusively fed human milk for 9 months need an additional source of iron after about 6 months of age.

Anemia, Hypochromic↗
PubMed1991

Race and birth weight: the Chinese example.

In several studies a race-specific variation in birth weight was suggested between black infants and white infants. The following were compared: (1) the birth weight of Chinese infants born in mainland China, Taiwan, and the United States; and (2) the birth weight of Chinese infants and white infants born in the United States controlled for sociodemographic background. Similar birth weight distributions and incidence of low birth weight were found among Chinese infants born in the three areas with markedly different economic conditions. The women in all three areas appear to have met the basic health and nutritional needs for adequate fetal growth. Similar incidence of low birth weight with different birth weight distribution was found among infants born in the United States to two Chinese parents, to one Chinese parent and one white parent, and to two white parents. The variation in birth weight is greater for white infants than for Chinese infants and, consequently, more white infants had larger birth weight. The possibility of race-specific influences on birth weight distribution is suggested by these findings.

Asian People↗
PubMed1990

The effect of cigarette smoking on hemoglobin levels and anemia screening.

The relationships among cigarette smoking, hemoglobin concentration, and carboxyhemoglobin concentration were examined using data from the Second National Health and Nutrition Examination Survey. Among women, smokers had a mean (+/- SE) hemoglobin level of 137 +/- 0.4 g/L, significantly higher than the mean hemoglobin level of 133 +/- 0.5 g/L for never-smokers. Among men, the mean hemoglobin levels for smokers and never-smokers were 156 +/- 0.4 and 152 +/- 0.5 g/L, respectively. No significant difference in mean hemoglobin was noted between ex-smokers and never-smokers. Mean hemoglobin levels and carboxyhemoglobin levels increased progressively with the number of cigarettes consumed per day. Cigarette smoking seems to cause a generalized upward shift of the hemoglobin distribution curve, which reduces the utility of hemoglobin level to detect anemia. Among women of comparable socioeconomic status, the prevalence of anemia was 4.8% +/- 0.6% among smokers, compared with 8.5% +/- 1.2% among never-smokers. This study suggests that minimum hemoglobin cutoff values should be adjusted for smokers to compensate for the masking effect of smoking on the detection of anemia.

Adolescent↗
PubMed1990

Effect of naloxone and prolonged preganglionic stimulation on noncholinergic transmission in the superior cervical ganglion of the cat.

In cats anesthetized with sodium pentobarbital, a supramaximal 40-Hz, 30-s train to the cervical sympathetic trunk, during block of ganglionic cholinergic transmission with hexamethonium and scopolamine, produced a delayed, slow, small amplitude contraction of the nictitating membrane that persisted for several minutes after the end of the stimulus train. The post-stimulus component of the response was due to afterdischarge of the ganglion cells, since section of the post-ganglionic axons at the end of the train resulted in elimination of this component. The amplitude of the slow nictitating membrane response was enhanced in a dose-dependent manner by i.v. injection of naloxone. The enhancement was detectable at a dose as low as 1 microgram/kg and was maximal at 10 micrograms/kg. During continuous preganglionic stimulation at 40 Hz, the amplitude of the slow nictitating membrane response reached a peak in 2-4 min and then faded with time until it became undetectable. Time for 90% decay was 82 +/- 5 min (n = 18). The nictitating membrane response to postganglionic nerve stimulation was not modified by prolonged preganglionic stimulation. In three cats, the cervical sympathetic trunk was split into two bundles and one bundle was stimulated continuously at 40 Hz until the slow response disappeared. At this time stimulation of the unconditioned bundle evoked a slow response of normal appearance. This suggests that the process underlying the fade involves only the conditioned axons. Recovery from the fade was slow, the response approaching control by 24 h post-stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Parent characteristics and sex differential infant mortality: the case in Tennessee.

Females survive males at most ages in virtually all modern industrialized societies. However, stratification of a sample by socioeconomic indicators shows that white infant male and female postneonatal mortality rates converge as the mothers' or parents' education rises and as the mothers age. These results are congruent with the parental selection hypothesis and with other findings that suggest that families at the pinnacle of the local social structure invest heavily in males and that parents nearing the end of their reproductive career try hard to effect the survival of all offspring.

Educational Status↗
PubMed1989

Growth of vegetarian children: The Farm Study.

To examine the effects of a vegetarian diet on child growth, height and weight data of 404 vegetarian children aged 4 months to 10 years who lived in a collective community in Tennessee were studied. Height for age, weight for age, and weight for height were compared with the US growth reference. Birth weights, infant feeding patterns, and parental heights were also evaluated in relation to growth. Most of the height for age, weight for age, and weight for height (n = 833) were within the 25th and 75th percentiles of the US growth reference. The mean height for age and weight for age, however, were slightly less than the median of the reference population. For different age groups, the mean height ranged from 0.2 to 2.1 cm and the mean weight ranged from 0.1 to 1.1 kg less than the reference median. The largest height difference was observed at 1 to 3 years of age and may be partly the result of intrinsic irregularities in the US growth reference at those ages. By 10 years of age, children from The Farm averaged 0.7 cm and 1.1 kg less than the reference median, representing only 0.1 and 0.3 SD from the reference. Thus, these children have adequate attained growth, even though it was modestly less than that of the reference population.

Adult↗