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Biomedical subjects

J Benson

Publications and source records attributed to J Benson.

At least 19 recordsLinked to original sources
PubMed1992

Use of the polymerase chain reaction to detect hypermethylation in the calcitonin gene. A new, sensitive approach to monitor tumor cells in acute myelogenous leukemia.

Based on the recent observations that, in a majority of patients with acute leukemia, the 5' end of the calcitonin gene was hypermethylated and abnormal DNA fragments were observed following HpaII restriction digestion, we have developed a PCR-based method to sensitively detect this abnormal methylation of the calcitonin gene in AML. Applying the concept of competitive PCR, a semi-quantitative correlation was obtained between the amount of hypermethylation and the amount of leukemic cells present. These results suggest that this method will be useful to monitor the amount of tumor cells in bone marrow from patients with AML.

Base Sequence↗
PubMed1990

Nutritional intake in adolescent athletes.

Nutrition plays a critical role in the success of the competitive adolescent athlete. Some groups have stricter nutrition requirements than others. The authors summarize nutrition intake data on serious female gymnasts, ballet dancers, and high-school cross-country runners. This article also discusses the nutritional needs of young male wrestlers and weightlifters.

Adolescent↗
PubMed1989

Gas exchange properties of goat hemoglobins A and C.

Hypoxic or anemic goats with the A hemoglobin genotype switch to the production of hemoglobin C, resulting in a reduced blood oxygen affinity. However, the physiologic consequences of this switch are not clear. We therefore studied the gas exchange properties of the two hemoglobin types. We found that purified hemoglobins A and C have very similar oxygen affinities and H+ Bohr effects, but in the presence of CO2, the affinity of hemoglobin C is substantially less than that of hemoglobin A. That this is not a nonspecific ionic effect is suggested by identical effects of NaCl on O2 binding to the two proteins and by a 2-fold higher capacity of hemoglobin C to bind CO2. The data can be explained by a class of CO2 binding sites in the beta C chain whose affinity is much higher than that of either of the primary sites or of those in Hb A. Our results suggest that in hemoglobin C-containing red cells CO2 acts as a potent allosteric effector, analogous to the role played by 2,3-diphosphoglycerate in human red blood cells. Goat hemoglobin C may have advantages over hemoglobins A or B in O2 transport under hypoxic conditions or in anemia.

Animals↗
PubMed1989

Generation of hybrid human immunodeficiency virus by homologous recombination.

Human immunodeficiency virus (HIV) type 1, isolated from diverse sources, exhibits genomic diversity. The mechanisms by which the genomic diversity takes place in individuals exposed to multiple virus isolates is yet to be elucidated. Genetic variation, in general, might result from mutagenic events such as point mutations, rearrangements (insertions and deletions), and recombination. In an attempt to evaluate the process of genetic diversity, we designed experiments to analyze recombination between HIV DNAs by using DNA transfection in cell cultures. Here we report the successful recombination between truncated HIV proviral DNAs with an overlap homology of 53 base pairs that leads to the formation of viable hybrid virus. Recombination was also seen between exogenous DNA introduced into cells and homologous HIV sequences resident in the cells. These results indicate that recombination among various HIV isolates may play a significant role in the generation of genetic diversity of HIV. Further, the method used here enables the construction of hybrid HIV genomes to identify the viral determinants responsible for tropism, replication, and cytopathic effects.

Base Sequence↗
PubMed1988

Squamous papilloma of the esophagus: a case report and review of the literature.

A case of squamous cell papilloma of the esophagus in a 70-yr-old white woman is reported. The literature is reviewed, summarized, and tabulated. This study found that the average age of a person with a squamous cell papilloma of the esophagus was 51.5 yr, with an associated male:female ratio of 1.8:1 (39M:22F). Additionally, most squamous papillomas were single (52) rather than multiple (9), most were located in the distal one-third of the esophagus (41), and symptoms at presentation were diverse, although epigastric pain was the chief complaint in 27 patients.

Aged↗
PubMed1987

Three-dimensional similarity mapping reveals nucleotide sequence relationships among human immunodeficiency virus (HIV) isolates.

A method has been developed to compare and graphically display comparisons between many related nucleotide sequences. Principal coordinate analysis, a multidimensional scaling technique, was used to display DNA homology data in three dimensions. Using these methods, an analysis of the env, gag, and gag/pol overlapping regions of human immunodeficiency virus (AIDS virus) clearly demonstrates a clustering of North American isolates relative to African isolates. Elements of the latter group are dissimilar to one another and to the North America group. For the env region, the North American isolates can be resolved into two distinct groups.

Base Sequence↗
PubMed1987

Comparative lung immunotoxicity of inhaled quartz and coal combustion fly ash.

Some inhaled particles that are deposited in the terminal airways and alveoli clear to the lung-associated lymph nodes, and insoluble particles have a long half-life in these tissues. Because the lung-associated lymph nodes are essential in the induction of immunity after lung immunization, the accumulation of inhaled particles in these tissues could alter immune responses that develop after lung immunization. This study evaluated the effects of inhaled insoluble fly ash particles or alpha quartz on the immune functions of lung-associated lymph nodes. F344 rats were exposed for 20 days by inhalation of fly ash from a fluidized bed combustor (FBC) or a pulverized coal combustor (PCC). Rats were similarly exposed to quartz particles (Min-U-Sil). Control rats were exposed to filtered air. Groups of ten exposed and ten control rats from each group were immunized by intratracheal instillation of 10(8) sheep red blood cells at 4, 6, 40, and 52 weeks after the start of exposures. The cellularity of the lung-associated lymph nodes and antibody-mediated immunity were evaluated at 7 days after immunization. Tissues from lung and lung-associated lymph nodes were taken for histopathology. The inhalation of FBC fly ash, PCC fly ash, and quartz particles all significantly increased the number of lymphoid cells in the lung-associated lymph nodes at each of the sacrifice times. However, FBC fly ash had no significant effect on antibody immunity, while both PCC fly ash and quartz caused suppression of antibody responses at 52 weeks after the start of exposure. Histopathology data showed that exposure to quartz and PCC fly ash caused significant cellular changes in lungs and lung-associated lymph nodes, while FBC fly ash had less effect. These data indicate that an acute exposure (20 days) to relatively insoluble particles significantly increased the cellularity of the lung-associated lymph nodes for up to 52 weeks after the start of the exposure, but the pulmonary toxicity of the particles inhaled appeared to influence the effects of the exposure on antibody immune responses.

Animals↗
PubMed1986

Task motivation and problem appraisal in long-term psychiatric patients.

Severely handicapped psychiatric patients in long-term day care were questioned about their perceptions of their skills, motivation to perform a range of everyday tasks, current problems and coping strategies. Patients were found to respond reliably and consistently to these questions. It is argued that effective service planning must take account of patients' views of their difficulties and, in particular, of their subjective priorities.

Activities of Daily Living↗
PubMed1986

Prognosis of the very low birthweight baby in relation to gender.

The effects of gender on mortality and morbidity of all neonates weighing less than 1500 g admitted to King's College Hospital Neonatal Intensive Care Unit during 1980-82 (n = 271) were examined. Very low birthweight boys had a significantly higher mortality and more postnatal complications than girls. The higher incidence of respiratory distress syndrome and pulmonary interstitial emphysema in boys was associated with increased mortality in the first year. Surviving boys had significantly more problems, including lower Apgar scores at five minutes, more frequent apnoeic attacks and bradycardic episodes, transient tachypnoea, neonatal anaemia, and lower blood calcium and phosphate concentrations. Surviving children were followed up at 1 and 2 years of age. Development of boys at 1 year was significantly delayed compared with girls in all fields save locomotor. Although at 2 years some of the differences had diminished, those in language and personal social skills were more pronounced. More than twice as many boys as girls had major neurodevelopmental disorders.

Child Development↗
PubMed1986

Medium-chain triglycerides in infant formulas and their relation to plasma ketone body concentrations.

A mild ketosis is known to prevail in the mother, fetus, and newborn infant during the 3rd trimester and in the early neonatal period. It has been shown that during an equivalent period in the rat ketone bodies are readily oxidized and serve as key substrates for lipogenesis in brain. Since medium-chain triglycerides are known to be ketogenic, preterm infants may benefit from dietary medium-chain triglycerides beyond the point of enhanced fat absorption. Our objective was to determine the ketogenic response in preterm infants (gestational age: 33 +/- 0.8 wk) fed three different isocaloric formulas by measuring the concentrations of 3-hydroxybutyrate and acetoacetate in the plasma of these infants. At the time of entrance to the study the infants were receiving 110 kcal/kg/24 h. Study I (11 infants): the infants were fed sequentially in the order; PM 60/40 (PM), Special Care Formula (SCF), and Similac 20 (SIM). In SCF greater than 50% of the fat consists of medium-chain length fatty acids while PM and SIM contain about 25%. The concentration of 3-hydroxybutyrate in plasma was significantly higher when infants were fed SCF than PM and SIM [0.14 +/- 0.03, 0.06 +/- 0.01, and 0.05 +/- 0.01 mM, respectively (p less than 0.01)]. Study II (12 infants); the infants were fed SCF, then SIM, or the reverse. The concentration of acetoacetate in plasma was 0.05 +/- 0.01 and 0.03 +/- 0.01 mM when infants were fed SCF and SIM, respectively (0.1 greater than p greater than 0.05). The concentrations of 3-hydroxybutyrate in plasma were similar to those measured in study I for the respective formulas.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1985

Disabilities in survivors of low birthweight.

A study of those survivors weighing 2000 g or less at birth born to residents of the South East Thames Regional Health Authority in 1970, '71, and '73 was carried out by abstracting data from health visitors' and school health records. Some postnatal information was available for 78% of the children. Prevalences of reported impairments in relation to birthweight were 20% in babies of 1500 g or less, 13% in the group weighing 1501 to 1750 g, and 11% for those of 1751 to 2000 g. Only half the impairments in the first group were likely to be seriously disabling, and only a fifth were of obvious prenatal origin. In the heaviest group, about 3% were likely to become severely disabled, but in over two fifths with impairment, this was likely to be of prenatal origin and therefore more difficult to prevent. This factor together with the larger number of survivors of birthweight 1751 to 2000 g than of 1500 g or less, indicate that an increase in impairments may be seen in the heavier group if their mortality continues to fall.

Birth Weight↗
PubMed1984

Lymphocytic myocarditis presenting as unexplained ventricular arrhythmias: diagnosis with endomyocardial biopsy and response to immunosuppression.

During a period of 18 months beginning in January 1982, a total of 65 patients were referred to the Miami Heart Institute for evaluation of either aborted out of hospital sudden death, ventricular tachycardia resistant to standard clinically directed antiarrhythmic medication programs or high grade ventricular arrhythmia (Lown class greater than or equal to IV B) with or without syncope. After complete evaluation including cardiac catheterization in all but 1 patient, 17 patients were identified in whom no obvious cardiac disease could be found. Twelve of the 17 underwent right ventricular endomyocardial biopsy. Six of the 12 biopsies demonstrated clinically unsuspected lymphocytic myocarditis (Group A). Findings in three of the remaining six biopsies were consistent with an early cardiomyopathy and in three were completely normal (Group B). Retrospective review of the clinical, laboratory, electrophysiologic, hemodynamic and angiographic data failed to identify a marker that reliably separated Group A from Group B patients. In addition to antiarrhythmic therapy guided by laboratory electrophysiologic study, all Group A patients were treated with prednisone and azathioprine. After 6 months of immunosuppression, all patients with myocarditis were reevaluated in the hospital without antiarrhythmic medication. Ventricular tachycardia/fibrillation could not be provoked in the laboratory during repeat electrophysiologic testing in five of the six patients. Repeat myocardial biopsy after all immunosuppressive therapy had been discontinued revealed absence of inflammation associated with varying degrees of residual interstitial fibrosis. There were no deaths. It was concluded that a patient with an otherwise clinically silent lymphocytic myocarditis can present with potentially life-threatening ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Lymphonodular hyperplasia of the colon as a pathologic finding in children with lower gastrointestinal bleeding.

The serious implication of gastrointestinal blood loss in children is well recognized; however, the significance of lymphonodular hyperplasia of the colon (LNHC) as a pathologic finding in this group of children is unclear. We reviewed the records of 95 children, ages 2-48 months, who were referred to our clinic with a history of hematochezia. Proctosigmoidoscopy was performed on 65 of them. Twenty children (31%) examined proctosigmoidoscopically were found to have LNHC, with no other identified source of bleeding. Clinical histories, endoscopic findings, and colonic biopsy specimens from the LNHC group were examined. Clinical presentation of patients in this group was not distinctive. LNHC was most prominent in the distal colon and rectum and was endoscopically characterized by friability (13/20) and ulceration (3/20). Characteristics of biopsy specimens from children with LNHC were than compared with tissue obtained from an age-matched control population and children with colitis. Biopsy specimens from children with LNHC contained increased numbers of lymphoid follicles and larger follicles than those from the control group. Specimens also contained mucosal inflammation and epithelial thinning and ulceration overlying enlarged follicles. We conclude that LNHC is a frequent proctosigmoidoscopic finding in children evaluated for lower gastrointestinal bleeding. The endoscopic and histologic appearance of these lesions would suggest that LNHC is not a normal finding and represents a potential source of rectal bleeding in children.

Acute Disease↗
PubMed1984

A malignant neoplasm with features of both squamous cell carcinoma and malignant melanoma.

A case of a malignant neoplasm with features suggestive of both malignant melanoma and squamous cell carcinoma is reported. The neoplastic cells were positive for both S-100 protein and keratin when stained by the indirect peroxidase-antiperoxidase method. The literature on other instances of bi- or multidirectional differentiation of neoplastic cells is reviewed. The significance of these findings for terminology of neoplasms is discussed.

Aged↗
PubMed1984

Saving sight.

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Corneal Transplantation↗