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Biomedical subjects

P Snyder

Publications and source records attributed to P Snyder.

At least 37 records · Page 2Linked to original sources
PubMed1993

Characterization of translational frame exception patients in Duchenne/Becker muscular dystrophy.

The clinical progression of Duchenne muscular dystrophy (DMD) patients with deletions can be predicted in 93% of cases by whether the deletion maintains or disrupts the translational reading frame (frameshift hypothesis). We have identified and studied a number of patients who have deletions that do not conform to the translational frame hypothesis. The most common exception to the frameshift hypothesis is the deletion of exons 3 to 7 which disrupts the translational reading frame. We identified a Becker muscular dystrophy (BMD) patient, an intermediate, and a DMD patient with this deletion. In all three cases, dystrophin was detected and localized to the membrane. One DMD patient with an inframe deletion of exons 4-18 produced no dystrophin. One patient with a mild intermediate phenotype and a deletion of exon 45, which shifts the reading frame, produced no dystrophin. Two patients with large inframe deletions had discordant phenotypes (exons 3-41, DMD; exons 13-48, BMD), but both produced dystrophin that localized to the sarcolemma. The DMD patient, 113, indicates that dystrophin with an intact carboxy terminus can be produced in Duchenne patients at levels equivalent to some Beckers. The dystrophin analysis from these patients, together with patients reported in the literature, indicate that more than one domain can localize dystrophin to the sarcolemma. Lastly, the data shows that although most patients show correlation of clinical severity to molecular data, there are rare patients which do not conform.

Adolescent↗
PubMed1993

Kennedy's disease: a clinicopathologic correlation with mutations in the androgen receptor gene.

We confirmed a mutation of the androgen receptor gene as the cause for Kennedy's disease, also called "X-linked recessive spinal and bulbar muscular atrophy" or "bulbospinal neuronopathy." The mutation is characterized by an increased size of a polymorphic tandem CAG repeat within the first exon of the gene. The study population consisted of 17 patients from seven families (five distinct kinships and two isolated cases). Two patients were as yet asymptomatic and had normal examinations. Four carrier females showed the mutant as well as the normal allele; none showed clinical features of Kennedy's disease. There was no large expansion of the mutation observed in three generations of one family. Phenotypic expression between and within families was variable and not related to the size of the mutation. This contrasts with the gene mutations found in myotonic dystrophy and fragile X syndrome, where increased severity of disease correlates with the number of tandem triplet repeats. The findings reported here appear to explain the failure to find genetic anticipation in Kennedy's disease. The DNA test for Kennedy's disease can now be used for definitive diagnosis and carrier detection. In addition, mutation analysis allows early detection, which has implications for potential treatment.

Creatine Kinase↗
PubMed1992

Transurethral electrical bladder stimulation: initial results.

Transurethral electrical bladder stimulation to rehabilitate the neurogenic bladder initially proposed by Katona has been promoted in the United States by Kaplan and Richards since the mid 1980s. Encouraged by their results, 2 1/2 years ago we instituted a program patterned on their experience. Since January 1989 we performed transurethral electrical bladder stimulation in 21 patients ranging in age from 4 months to 26 years. The cause of the neurogenic bladder was myelomeningocele in 16 patients, lipomeningocele in 4 and an incomplete spinal cord injury in 1. The stimulation was performed using equipment supplied by Kaplan and Richards, and the stimulation protocol followed their recommendations. The treatments were delivered in daily sessions of 90 minutes with about 20 sessions in a series. Of the patients 11 have undergone 1,6 have finished 2 and 4 have completed 3 series of stimulation. The ultimate objective of the program is to achieve volitional voiding. To reach that goal the stimulation must engender a bladder contraction that must then be perceived and ultimately controlled. Of our patients 20 (95%) achieved bladder contractions during stimulation, including 12 (60%) who had either a definite (7) or probable (5) sense of these contractions. To date, only 1 patient has started the biofeedback program to attempt to modify detrusor activity and he is presently wet on clean intermittent catheterization. Parents of 5 other children report minor positive changes in the child's perception of the bladder activity. Three patients noticed an improvement in the bowel program, although the effect only lasted during the month of stimulation in 1. Cystometrograms were performed before each series of treatments. Of the 10 patients with serial studies 2 had significant increases in bladder capacity and 3 demonstrated a clinically significant decrease in the end filling pressures. We have seen limited encouraging results from transurethral electrical bladder stimulation. This is a time-consuming, labor intensive program, and the parents and patients need to be informed of the actual potential for dramatic improvements.

Adolescent↗
PubMed1988

Terbutaline and diaphragm function in chronic obstructive pulmonary disease: a double-blind randomized clinical trial.

We conducted a double-blind, randomized crossover trial to evaluate whether oral terbutaline (2.5 mg orally three times daily for a week) increased the force of diaphragmatic contraction in normocapnic patients with chronic obstructive pulmonary disease. Ten patients with moderate to severe airway obstruction completed the trail. Compared with placebo, terbutaline produced a mean increase of 5.8 cmH2O in peak inspiratory mouth pressure and a mean increase of 5.0 cmH2O in transdiaphragmatic pressure during a maximal inspiratory manoeuvre. These small changes with terbutaline failed to achieve statistical significance. Also, terbutaline failed to alter flow rates (FEV1, Vmax50) or patients' dyspnoea ratings using two separate clinical scales (Pneumoconiosis Research Unit Score and the Modified Dyspnoea Index). Because all observed changes in respiratory muscle strength were small and because the trial had power to detect small changes in inspiratory mouth pressures, we suggest that oral terbutaline at the dose administered in this study has little noteworthy effect on respiratory muscle strength in normocapnic patients with chronic obstructive pulmonary disease.

Aged↗
PubMed1986

In vitro production of anti-influenza virus antibody after simultaneous administration of H3N2 and H1N1 cold-adapted vaccines in seronegative children.

Sixteen doubly seronegative (H3N2 and H1N1) young children were recently enrolled in a study of live, attenuated cold-adapted influenza A vaccines. Twelve children received simultaneously H3N2 and H1N1 live, attenuated influenza vaccine intranasally and four received saline as placebo controls. Peripheral blood lymphocytes (PBL) were obtained sequentially from all children and the in vitro production of anti-influenza H3N2 and H1N1 antibody from unstimulated and influenza stimulated cells was measured by ELISA. In vitro antibody studies were performed at 0, 2, 4, and 12 weeks after immunization. PBL from six of 12 children spontaneously produced H3N2 antibody and eleven of 12 produced H1N1 antibody. Influenza stimulation of PBL induced antibody production in 8/12 for H3N2 and 12/12 for H1N1. PBL from all four placebo immunized children failed to produce specific influenza antibody in vitro at any time studied. In vitro antibody produced after immunization was primarily of the IgG isotype with peak production occurring at 4-12 weeks, supporting the primary nature of the response. The correlation between the presence of positive serum HAI and ELISA titres, and the production of in vitro antibody was good for both H3N2 and H1N1 vaccines. In summary, the simultaneous administration of two attenuated influenza A vaccines into the upper respiratory tract of seronegative children resulted in the stimulation of PBL capable of secreting both H3N2 and H1N1 influenza specific antibody in vitro.

Antibodies, Viral↗
PubMed1986

Acute effects of passive smoking on lung function and airway reactivity in asthmatic subjects.

We studied the acute effects of one hour of passive cigarette smoking on the lung function and airway reactivity of nine young adult asthmatic volunteers. At the time of this study, the subjects were asymptomatic and had normal or nearly normal lung function. Passive smoking produced no change in expiratory flow rates. However, there was a small decrease in nonspecific bronchial reactivity, as assessed by methacholine inhalation challenge testing (p = 0.022). Pharmacologically active substances present in cigarette smoke, such as nicotine, may explain the observed change in airway reactivity. Although the finding of decreased airway reactivity might suggest that passive smoking produces a "protective" effect on the underlying asthma, the observed change in reactivity was slight and of uncertain clinical significance. We conclude that passive smoking presents no acute respiratory risk to young asymptomatic asthmatic patients.

Adult↗
PubMed1984

Influence of exercise on urea, creatinine, and 3-methylhistidine excretion in normal human subjects.

To evaluate the effects of exercise on net protein catabolism, the losses of urea in sweat and urine and urinary creatinine and 3-methylhistidine (3MH) excretion were determined in eight healthy subjects during cycle ergometer exercise performed at approximately 45% of VO2max for 90 min. The subjects ingested a meat-free diet for 5 days starting 3 days before and continuing for 1 day after the day of exercise. During exercise, total urea excretion (urine + sweat losses) increased 100% above pre- and postexercise values. Thirty percent of the total urea excretion during exercise was in the form of sweat losses. Total protein breakdown (as reflected by urea excretion), however, could account for less than 5% (21 +/- 4 kcal) of total calorie expenditure during the exercise (567 +/- 83 kcal). Urinary creatinine excretion increased by 50% during exercise. Urinary excretion of 3MH also tended to rise, but the ratio of urinary 3MH to creatinine showed no change in response to exercise. We conclude that 1) light to moderate exercise results in an increase in net protein catabolism and an increase in creatinine excretion; 2) sweat losses are an important route for urea excretion during exercise; 3) there is no evidence of a disproportionate increase in breakdown of myofibrillar contractile proteins; and 4) in spite of the increase in the rate of protein catabolism, protein is only a minor source of energy during light to moderate exercise.

Adolescent↗
PubMed1983

A neuroendocrine test battery in bipolar patients and healthy subjects.

Abnormalities of hormonal responses to a number of neuroendocrine challenges have been reported in depressed patients. Most studies have examined responses in a single neuroendocrine axis. We used a series of four neuroendocrine challenges (thyrotropin-releasing hormone test, gonadotropin-releasing hormone test, insulin tolerance test, and dexamethasone suppression test) to examine eight hormonal responses in 22 healthy subjects and 22 patients with bipolar disorder. Variability of hormonal responses in bipolar patients was examined by evaluating the number of abnormal hormonal responses as compared with responses from healthy volunteers. Abnormalities were observed after all four neuroendocrine tests. Nine control subjects (40.9%) and 17 bipolar patients (77.3%) had at least one abnormal response. More strikingly, 12 bipolar patients (54.5%), but no controls, had two or more abnormal responses. These findings suggest that manic-depressive patients show increased variability in hormonal response from multiple neuroendocrine axes.

Adult↗
PubMed1983

The use of nonprescribed treatments by hemodialysis patients.

In an attempt to examine the extent to which a specific chronically ill population might be engaged in self care through the use of nonprescribed treatments, 230 adult hemodialysis patients in Hawaii were interviewed. Information about the use of various treatment methods was correlated with sociodemographic characteristics, and the chi-square test of significance was applied to selective findings. Within this multiethnic patient population, 74% indicated they had tried one or more nonprescribed treatments for their kidney failure, and the majority of individuals judged their efforts to be effective. Ethnicity was not a significant determinant in the tendency to use nonprescribed treatments, although it influenced the selection of specific methods. Other sociodemographic characteristics were also found to be of minimal value as predictors of this type of help seeking behavior. The illness experience itself overrides many of the sociocultural factors in this study.

Adolescent↗
PubMed1983

Neuroendocrine regulation in depressed postmenopausal women and healthy subjects.

Results from prior studies utilizing gonadotropin-releasing hormone (GnRH) in affective illness have been contradictory. There have been no systematic investigations of multiple pituitary hormonal responses to GnRH infusion in either depressed or healthy postmenopausal women. Potential abnormalities in the hypothalamic-pituitary-gonadal (HPG) axis may be limited to postmenopausal women who lack the estradiol feedback influence at the pituitary level. We therefore studied 18 depressed and nine healthy postmenopausal women with the GnRH infusion test and measured LH, FSH, prolactin, growth hormone, and thyrotropin responses. Our findings confirmed earlier reports of a lower basal LH concentration in postmenopausal depressed subjects. GnRH stimulated release of LH, FSH, and prolactin in both patients and controls; however, there were no differences in the mean peak hormone values between groups.

Depressive Disorder↗
PubMed1982

Growth hormone, prolactin and thyrotropin responses to gonadotropin-releasing hormone in depressed patients and healthy volunteers.

Growth hormone (GH), prolactin (PRL) and thyrotropin (TSH) release following gonadotropin-releasing hormone (GnRH) administration were examined in 56 patients with major affective disorder (37 unipolar, 19 bipolar) and 38 normal healthy subjects. There were no differences in GH, PRL or TSH responses after GnRH infusion between the patients and the normal subjects, in contrast to previously reported abnormalities in depressed patients. Serum GH concentration increased after GnRH in both normal and depressed men; serum TSH increased after GnRH in both normal women and bipolar women, but not in unipolar depressed women. Further studies comparing GnRH to saline infusion will be necessary to determine if the GH and TSH responses seen in this study are due to GnRH or result from the stress of the experimental procedures.

Adult↗