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Biomedical subjects

L H Allen

Publications and source records attributed to L H Allen.

At least 73 records · Page 4Linked to original sources
PubMed1991

Fiber digestibility and breath-hydrogen excretion in subjects consuming rural and urban Mexican diets.

Apparent digestibility of dietary fiber and its effect on breath-hydrogen excretion and gastrointestinal symptoms were determined in 16 subjects consuming a plant-based rural Mexican diet (RMD) and a more refined urban Mexican diet (UMD). Neutral-detergent-fiber intake and digestibility were 40.2 and 22.7 g/d (56%) for the RMD and 12.1 and 8.9 g/d (70%), respectively, for the UMD. Apparent digestibilities of hemicellulose, cellulose, and lignin were 40%, 63%, and 53% from the RMD and 73%, 75%, and 58%, respectively, from the UMD. Total breath-hydrogen excretion during 10 postprandial h was similar after both diets, showing that the breath-hydrogen test is of limited value for comparing carbohydrate fermentation from mixed diets. Mouth-to-colon transit time was 5.7 and 6.5 h for the RMD and UMD, respectively (P less than 0.05). There were significantly more gastrointestinal symptoms with the RMD (P less than 0.01); however, neither diet caused symptoms indicative of serious gastrointestinal discomfort.

Adolescent↗
PubMed1990

Functional indicators and outcomes of undernutrition.

The advantages and limitations of using functional methods are discussed in the context of identifying undernutrition and hunger in children in the United States. At this time many of these methods have been used only in developing countries where undernutrition is more serious. However, there is great need to investigate whether, when and how undernutrition in the United States affects children's development. Functional measures can detect undernutrition and hunger in some situations where biochemical or clinical measures cannot.

Child↗
PubMed1989

A cautionary note on the use of autoregressive models in analysis of longitudinal data.

Rosner et al. presented a simple, easily implemented modelling method for retaining time order relationships in analyses of longitudinal data when successive measures are correlated. Evaluation of time order is particularly useful in epidemiologic studies concerned with exposure to potentially toxic substances and subsequent outcome, but may also have use in more traditional growth studies that relate intake to subsequent development. The analysis allows for unequally spaced measures and missing data. The estimation method permits varying numbers of observations per subject and, with measures equally spaced, one can fit the model with use of ordinary least squares regression software. We report on a potential false association that can result when both exposure and outcome are related to time. We illustrate this problem with a small scale simulation and example. We also note a more serious problem with Rosner's approach in interpreting parameters. Although the model may be useful for prediction, parameters depend on the autocorrelation and are not readily interpretable. We recommend alternative modelling strategies be used when autocorrelation of errors is suspected.

Age Factors↗
PubMed1988

Comparative effects of meals high in protein, sucrose, or starch on human mineral metabolism and insulin secretion.

Protein, carbohydrates, and amino acids produce calciuria by decreasing renal calcium reabsorption. This study compared the postprandial calciuretic and serum insulin responses of 12 adults to isocaloric meals: Control, High Protein, High Sucrose, and High Starch. In 3 h 60% more Ca was excreted after High Protein than after other meals; renal Ca reabsorption was lower after High Protein than after High Sucrose at 2.5 h and after High Starch and High Sucrose at 3 h (p less than 0.01). Insulin was higher after High Starch and High Sucrose than after High Protein. Urinary phosphorus excretion was lower 1-3 h after High Protein than after other meals (p less than 0.01). High Protein increased urinary potassium and zinc. Urinary Ca correlated significantly with urinary Zn (r = 0.64) and sodium (r = 0.62), peak serum P (r = -0.29), and serum insulin increase for Control (r = 0.70) and High Protein (r = 0.68) only. Insulin inhibition of Ca reabsorption is not the sole explanation of macronutrient-induced calciuria.

Adult↗
PubMed1988

Effects of CO(2) Concentration on Rubisco Activity, Amount, and Photosynthesis in Soybean Leaves.

Growth at an elevated CO(2) concentration resulted in an enhanced capacity for soybean (Glycine max L. Merr. cv Bragg) leaflet photosynthesis. Plants were grown from seed in outdoor controlled-environment chambers under natural solar irradiance. Photosynthetic rates, measured during the seed filling stage, were up to 150% greater with leaflets grown at 660 compared to 330 microliters of CO(2) per liter when measured across a range of intercellular CO(2) concentrations and irradiance. Soybean plants grown at elevated CO(2) concentrations had heavier pod weights per plant, 44% heavier with 660 compared to 330 microliters of CO(2) per liter grown plants, and also greater specific leaf weights. Ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) activity showed no response (mean activity of 96 micromoles of CO(2) per square meter per second expressed on a leaflet area basis) to short-term ( approximately 1 hour) exposures to a range of CO(2) concentrations (110-880 microliters per liter), nor was a response of activity (mean activity of 1.01 micromoles of CO(2) per minute per milligram of protein) to growth CO(2) concentration (160-990 microliters per liter) observed. The amount of rubisco protein was constant, as growth CO(2) concentration was varied, and averaged 55% of the total leaflet soluble protein. Although CO(2) is required for activation of rubisco, results indicated that within the range of CO(2) concentrations used (110-990 microliters per liter), rubisco activity in soybean leaflets, in the light, was not regulated by CO(2).

Journal Article↗
PubMed1988

Lactation outcome in insulin-dependent diabetic women.

To document the incidence and management of breast feeding among women with insulin-dependent diabetes mellitus (IDDM), 30 IDDM mothers and 30 controls were followed from birth of their infants to 6 weeks postpartum. The researchers interviewed the mothers in the hospital and by telephone at 1, 2, and 6 weeks postpartum. Fifty-three percent of the IDDM women and 57% of the general hospital population intended to breast feed. Because of the need for neonatal observation for hypoglycemia, most IDDM mothers were separated from their infants for the first 2 days. After 1 week, as many IDDM mothers as controls nursed. Initially, no differences in breast-feeding problems were found between the groups, but between 2 and 6 weeks postpartum, two IDDM nursing mothers but none of the controls experienced clinically diagnosed mastitis. A daily diet prescription of 31 kcal per kilogram of maternal body weight was associated with IDDM mothers' ability to sustain lactation, in contrast with 25 kcal per kilogram of maternal weight for IDDM mothers who stopped nursing. Six-week postpartum fasting plasma glucose levels of IDDM mothers who exclusively breast fed were significantly lower (4.6 +/- 2.2 mmol/L [82 +/- 40 mg/dl]) than the glucose levels of the women who stopped nursing (8.1 +/- 2.1 mmol/L [145 +/- 37 mg/dl]) or the glucose levels of the IDDM mothers who chose to bottle feed (6.7 +/- 1.7 mmol/L [120 +/- 30 mg/dl]). It appears that adequate maternal calories, blood sugar control, early breast stimulation, and mastitis monitoring are necessary for optimal lactation outcome in insulin-dependent diabetic women.

Blood Glucose↗
PubMed1988

Orbital pseudotumors.

Orbital pseudotumor is a clinical entity characterized by features of a space-occupying, non-specific inflammatory condition of the orbit. Diagnosis can be difficult, and the patient will often initially present to the otolaryngologist as an orbital complication of sinus disease, or as a severe upper respiratory tract infection. The recent experience of orbital pseudotumors at our center is presented with emphasis on the diagnosis and management of the disease process.

Adult↗
PubMed1987

Prevalence and age at development of enamel hypoplasias in Mexican children.

Enamel hypoplasias, deficiencies in enamel thickness resulting from disturbances during the secretory phase of enamel development, are generally believed to result from nonspecific metabolic and nutritional disruptions. However, data are scare on the prevalence and chronological distributions. of hypoplasias in populations experiencing mild to moderate malnutrition. The purpose of this article is to present baseline data on the prevalences and chronological distributions of enamel hypoplasias, by sex and for all deciduous and permanent anterior teeth, in 300 5 to 15-year-old rural Mexican children. Identification of hypoplasias was aided by comparison to a published standard (Federation Dentaire Internationale: Int. Dent. J. 32(2):159-167, 1982). The location of defects, by transverse sixths of tooth crowns, was used to construct distributions of defects by age at development. One or more hypoplasias were detected in 46.7% (95% CI = 40.9-52.5%) of children. Among the unworn and completely erupted teeth, the highest prevalence of defects was found on the permanent maxillary central incisors (44.4% with one or more hypoplasias), followed by the permanent maxillary canine (28.0%) and the remaining permanent teeth (26.2 to 22.2%) Only 6.1% of the completely erupted and unworn deciduous teeth were hypoplastic. The prevalence of enamel defects on the permanent teeth was up to tenfold greater than that found in studies of less marginal populations that used the FDI method. The prevalence of defects in transverse zones suggests a peak frequency of hypoplasias during the second and third years for the permanent teeth, corresponding to the age at weaning in this group. In the deciduous teeth, a smaller peak occurs between 30 and 40 weeks post gestation. The frequency of defects after three years of age is slightly higher in females than males, suggesting a sex difference in access to critical resources.

Adolescent↗
PubMed1987

Milk consumption, symptom response, and lactose digestion in milk intolerance.

The experience of adverse gastrointestinal symptoms (gas, abdominal pain, and diarrhea) after the oral ingestion of 360 mL whole milk was investigated in 25 adults who claimed to be milk intolerant. The level of customary milk consumption by all subjects was low compared with that of 13 control subjects who denied a history of milk intolerance. After drinking the milk, which was accompanied by a hydrogen breath test, most of the subjects experienced some of their accustomed intestinal discomfort and the degree of intolerance was similar for the nine (36%) who proved to be true lactose-maldigester subjects and the 16 (64%) who had flat hydrogen breath responses, ie, who were classified as lactose-digester subjects. There is a subpopulation of lactose-intolerant milk-rejector individuals that absorbs lactose efficiently and responds to other milk-related factor(s) with the same subjective symptoms and dietary conduct as do true lactose-maldigester individuals.

Adult↗
PubMed1987

Sucrose ingestion, insulin response and mineral metabolism in humans.

The effects of sucrose ingestion on the excretion of urinary calcium, zinc, phosphorus, sodium and potassium have been investigated and compared among 13 individuals to the magnitude of their postprandial serum insulin response. Fasted subjects consumed a beverage containing 2 g sucrose/kg, and urine and blood samples were taken at intervals during the next 3 h. As a result of sucrose consumption there were significant increases in serum insulin and decreases in serum phosphorus, but no change in serum total or filterable calcium, zinc, sodium or potassium. Urine calcium peaked at 1.5 h and was significantly increased from 10 through 2.5 h. Sucrose-induced increases in serum insulin and urine calcium were highly variable among subjects, and within the group were significantly correlated (r = 0.82, P less than 0.01). Urine calcium excretion was correlated with serum phosphorus (r = 0.41, P less than 0.05) and urine zinc (r = 0.80, P less than 0.01). Sucrose consumption also increased the urinary excretion of zinc and sodium, although renal reabsorption was not impaired. The effects of sucrose on urinary calcium are consistent with the hypothesis that insulin inhibits renal calcium reabsorption.

Absorption↗
PubMed1987

Drought Stress and Elevated CO(2) Effects on Soybean Ribulose Bisphosphate Carboxylase Activity and Canopy Photosynthetic Rates.

Soybean (Glycine max [L.] cv Bragg) was grown at 330 or 660 microliters CO(2) per liter in outdoor, controlled-environment chambers. When the plants were 50 days old, drought stress was imposed by gradually reducing irrigation each evening so that plants wilted earlier each succeeding day. On the ninth day, as the pots ran out of water CO(2) exchange rate (CER) decreased rapidly to near zero for the remainder of the day. Both CO(2)-enrichment and drought stress reduced the total (HCO(3) (-)/Mg(2+)-activated) extractable ribulose-1,5-bisphosphate carboxylase (RuBPCase) activity, as expressed on a chlorophyll basis. In addition, drought stress when canopy CER values and leaf water potentials were lowest, reduced the initial (nonactivated) RuBPCase activity by 50% compared to the corresponding unstressed treatments. This suggests that moderate to severe drought stress reduces the in vivo activation state of RuBPCase, as well as lowers the total activity. It is hypothesized that stromal acidification under drought stress causes the lowered initial RuBPCase activities. The K(m)(CO(2)) values of activated RuBPCase from stressed and unstressed plants were similar; 15.0 and 12.6 micromolar, respectively. RuBP levels were 10 to 30% lower in drought stressed as compared to unstressed treatments. However, RuBP levels increased from near zero at night to around 150 to 200 nanomoles per milligram chlorophyll during the day, even as water potentials and canopy CERs decreased. This suggests that the rapid decline in canopy CER cannot be attributed to drought stress induced limitations in the RuBP regeneration capability. Thus, in soybean leaves, a nonstomatal limitation of leaf photosynthesis under drought stress conditions appears due, in part, to a reduction of the in vivo activity of RuBPCase. Because initial RuBPCase activities were not reduced as much as canopy CER values, this enzymic effect does not explain entirely the response of soybean photosynthesis to drought stress.

Journal Article↗
PubMed1987

Plasma cell granuloma of the lacrimal sac.

A 31-year-old man with a 2-year history of recurrent dacryocystitis underwent dacryocystorhinostomy. An unexpected operative finding was a polyp in the lacrimal sac. Histopathological examination revealed a plasma cell granuloma. The nature of this uncommon inflammatory pseudotumour of the lacrimal sac is discussed.

Adult↗
PubMed1987

Biological and sociocultural determinants of successful lactation among women in eastern Connecticut.

Postpartum factors affecting the duration of lactation were identified for 250 women through a telephone survey. The survey examined the behaviors and attitudes of women who had chosen to nurse and who were still nursing at 2 weeks postpartum. Sixty percent of the mothers nursed their infants after delivery. However, by 10 weeks postpartum, only 34% of the babies were still breast fed. By self-report, the most significant factors associated with the maintenance of lactation at 10 weeks were related to perinatal hospital protocol, especially letting the infant suckle soon after birth. Other significant predictors of successful lactation outcome included early milk "let down," little use of supplemental formula, the mother's expectation at parturition of an extended nursing period, her feeling well and being satisfied with her body weight, her previous successful experience with lactation, and her perception that she feeds her infant on demand. Few of the women who had stopped nursing after 2 weeks sought advice on breast feeding from anyone other than the pediatrician. Most coped with their nursing problems themselves. The data reinforce the importance of labor and delivery practices that support early maternal-infant contact. They also suggest the use of infant health indexes and weight and height percentile placement records rather than reliance solely on weight gain as the index of lactation adequacy. Further, they indicate the need for clinical intervention before 2 weeks postpartum.

Attitude to Health↗
PubMed1986

Malignant melanoma of the eyelid and conjunctiva.

Four patients with malignant melanoma of the eyelid skin and 14 patients with conjunctival malignant melanoma are presented. Surgery was recommended for eyelid lesions and local excision followed by cryotherapy for conjunctival lesions. One patient with an eyelid skin malignant melanoma died and two patients with extensive malignant melanoma of the conjunctiva died. Nodular lesions involving the lid margin have the worst prognosis of eyelid skin malignant melanomas, and the greater the extent of conjunctival involvement the worse the prognosis for conjunctival malignant melanomas. The complications of cryotherapy are minor, but the follow-up period in this series is too short to comment on survival times.

Adult↗
PubMed1985

Supervoltage radiotherapy for Graves' ophthalmopathy: CCABC technique and results.

A treatment technique employing retrobulbar supervoltage radiotherapy (XRT) in Graves' ophthalmopathy is described. Twenty-eight patients have been treated and followed between 1980-1983. Twenty-six of 28 patients (93%) showed some response, with 19/28 (68%) having a good to excellent response. Four of 28 (14%) had recurrent symptoms post-XRT. Soft tissue signs and symptoms were relieved and disease progression arrested in the majority of patients, but proptosis and ophthalmoplegia responded poorly. High dose corticosteroids have generally been the alternative form of therapy for this disease. Post-XRT, 24/28 (86%) of patients have had no further steroid requirements, and been spared the associated complications. Treatment was well tolerated, with only five patients (18%) demonstrating a transient worsening of symptoms which settled entirely within 2 weeks. No long-term complications have been encountered. Eleven patients had post-XRT CT scans which were compared to pre-treatment scans and clinical response. Nine of 11 patients (82%) had CT changes in general agreement with the observed clinical response, but the degree of involvement seen on the initial CT scan was not predictive of response nor the risk of relapse. XRT with the described technique is felt to be an effective, safe, and practical approach to the disabling and disfiguring complications of severe Graves' ophthalmopathy.

Adult↗