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Biomedical subjects

J Snyder

Publications and source records attributed to J Snyder.

At least 73 records · Page 4Linked to original sources

The effects of consequences on patterns of social interaction: a quasi-experimental approach to reinforcement in natural interaction.

Research on social interaction has consistently documented the existence of mutual interdependencies between the behavior of 1 person and reactions to that behavior by others in the social environment. The concept of social reinforcement, although often used to explain acquisition and change in interaction patterns defined by such interdependencies, is difficult to apply to interaction observed in natural settings. On the basis of extended observation of the interaction of 2 mother-child dyads, the procedures needed to assess the effects of naturally occurring consequences on interactional patterns are detailed in this study. Reliable mother action-child reaction patterns were first identified, and the effect of maternal consequences for those patterns on the probability of their subsequent occurrence was assessed. Positive consequences were associated with increases, and negative consequences with decreases, in the probability of a child reacting to the next occurrence of the maternal action when compared to the base-rate probability of that action-reaction pattern. Thus consequences affect momentary shifts around the baseline probability of interactional patterns. Positive consequences were also associated with short-term increases, and negative consequences with short-term decreases, in the base-rate probability of interactional patterns.

Adult↗

alpha-Thalassemia hydrops fetalis: clinical and ultrasonographic considerations.

Five pregnant Southeast Asian women presenting during a 14-month period with microcytic anemia, preeclampsia, and size-date discrepancies were all ultimately diagnosed as carrying fetuses with homozygous alpha-thalassemia hydrops fetalis. The perinatal complications of this hemoglobin disorder are unique to persons of this ethnic background and include uniform fatality for the affected infant, maternal preeclamptic morbidity, and retained placenta. In this report the obstetric ultrasound findings are presented and the clinical manifestations are discussed, with recommendations made to reduce this emerging public health problem in the United States.

Adult↗

Childhood ingestions as symptoms of family distress.

Familial, child developmental, and demographic concomitants of serious ingestions in preschool children were measured in 23 hospitalized children and controls matched on age, race, and socioeconomic status. A precoded maternal interview focused on family stress, parental discipline, parental emotional history, as well as childhood temperament and social maturity. A regression analysis was performed on variables that discriminated between ingestion cases and controls. Sixteen variables from the regression equation were entered into a stepwise discriminant function analysis. Significant descriptors of ingestion victims included the following: lack of extended family low Vineland Social Maturity quotient, few maternal opportunities to escape caregiving, good health, a high frequency of physical punishment in the mother's childhood, and increased current advocacy needs. Using these six variables as a screening device, the discriminant function correctly classified 87% of the subjects as either cases or controls. These data suggest that ingestions are symptoms of familial and, especially of maternal, distress. These healthy, active, but delayed children appear to overwhelm their caregivers.

Child Abuse↗

Office audiometry.

The selection of appropriate hearing test procedures is dependent upon the goals chosen by the practitioner and the skills of the examiner. Office audiometry is superior to tuning-fork tests and provides unique information for diagnosis and management.

Audiometry↗

Behavioral effects of circumcision with and without anesthesia.

The behavior of full-term neonates undergoing circumcision with and without local anesthesia was examined using the Brazelton Neonatal Assessment Scale (BNAS). Evaluations were done blindly pre-and postcircumcision and on the day following the procedure. Infants receiving lidocaine in a dorsal penile nerve block (DPNB) remained more attentive to animate and inanimate stimuli following circumcision and demonstrated a greater ability to quiet themselves when disturbed. The smoothness and maturity of motor behaviors showed the expected rate of improvement or recovery curve in the anesthetized group, while the control group's behavior did not. Behavioral differences were still evident on the day following the procedure. This report adds to the growing body of data that indicate that circumcision is a painful procedure that disrupts the course of behavioral recovery following birth. These disruptions can be lessened by the use of local anesthesia to relieve pain and stress during the procedure without any additional morbidity. These data support the use of DPNB during anesthesia for routine neonatal circumcisions still requested by the majority of parents in the country.

Anesthesia, Local↗

Thyroid remnant ablation: questionable pursuit of an ill-defined goal.

Ablative therapy with I-131 in 30-mCi doses, directed to postsurgical remnants in patients with differentiated thyroid cancer, reduced visible I-131 uptake to zero or nearly zero in 81% of patients but did not protect against tumor recurrence in six of 69 patients who were followed for 2-5 yr. Recurrences developed within 5-37 mo. Effectiveness of 30-mCi doses of I-131 in producing ablation did not correlate with I-131 uptake by the thyroid remnant, surgeon's estimate of remnant size, or delivered dose to the remnant in rads, calculated using reasonable assumptions. These findings emphasize the difficulty of dosimetric measurements and calculations. The value of postsurgical ablative therapy in diminishing morbidity and mortality in patients with differentiated thyroid cancer has not yet been firmly established, and until this is done we advocate a conservative, economical approach to thyroid ablation with 30-mCi treatment doses of I-131 and 1-mCi neck-scanning doses to check on effectiveness of therapy.

Adenocarcinoma↗

Demographic, cognitive and experiential predictors of presurgical anxiety.

A heterogeneous sample completed a demographic survey, a measure of internal-external locus of control (I-E), the Hospital Stress Rating Scale (HSRS), and a state anxiety measure on the eve of major surgery. Three sets of variables (demographic, cognitive, and experiential) together significantly accounted for one-quarter of the variance in state anxiety. However, only the cognitive set (I-E and the HSRS) was uniquely significant, supporting the view of presurgical anxiety as a patient's response to interpretation of a life-threatening event. Higher levels of anxiety were associated with more anticipated stressful experiences, stronger beliefs that powerful others and chance influence events, and weaker beliefs that events are caused by one's own efforts. Implications are presented for identifying patients at risk for presurgical anxiety and for designing interventions to enhance the patient's sense of control.

Adult↗

An international collaborative clinical study mechanism for resuscitation research.

Recent experimental and clinical studies of cardiac arrest, suggesting a brain damage ameliorating effect of thiopental loading, stimulated the development of an international randomized clinical trial of brain resuscitation. Twelve collaborating hospitals in 9 countries are testing the efficacy of post-cardiac arrest thiopental loading (30 mg/kg body wt). The methodology for assessing insult and outcome data, as well as risk and benefit monitoring, is described. This clinical trial will be completed in 1983 and is expected to provide valuable data about the efficacy of thiopental loading. The study mechanism is now well-established and ready for the evaluation of future promising brain resuscitation therapies.

Clinical Trials as Topic↗

Correlative light and electron microscopy of dissociated immature rat testicular cells undergoing morphogenesis in vitro.

Immature rat testicular cells undergo morphogenesis in primary culture (Davis, 1978). Depending upon the number of dissociated testicular cells added to the culture dish, spherical or tubular aggregates were formed. Spherical aggregates resulted from movement of cells into centers of aggregation and the detachment of these cells from the substratum; on the other hand, tubular aggregates resulted from detachment and retraction of the cell monolayer at certain points along its outer edge. In this investigation, the different methods of formation of aggregates by immature rat testicular cells in primary culture were examined with the scanning electron microscope (SEM). The cell types involved in such morphogenesis and their associations within completely formed structures were examined by transmission electron microscopy (TEM). In addition, the rates of formation of aggregates were established by time-lapse cinemicroscopy. During formation of spherical aggregates, the rate of recruitment of cells into centers of aggregation (0.4 +/- 0.006 micrometer/min; means +/- S.E.M., n = 78) was much slower than the rate of cell detachment during formation of tubular aggregates (11.7 +/- 1.8 micrometer/sec; means +/- S.E.M., n = 110). Although specific roles for each cell types in formation of aggregates have not been determined, the associations of cells within the two types of reformed aggregates appeared to be similar. Myofibroblast cells were located in outer cell layers and Sertoli cells were observed to underlie the layers of myofibroblasts in both types of aggregates. Germinal cells, however, were found on the outer surface of spherical aggregates, but in tubular aggregates they were located on the inner surface. Since spherical and tubular aggregates are formed by different methods, this observation suggests that rearrangement of cells, within the aggregates takes place and contributes to the internal morphology of newly formed aggregates.

Animals↗

A new test of visual acuity using a holographic phase grating and a laser.

A new visual acuity testing device is able to determine a specific visual acuity of the retina even in the presence of opacities of the ocular media, such as a cataract. This is achieved by forming two spatially coherent, quasimonochromatic point sources near the nodal point of the eye. The two spherical waves that emanate from the point sources interact to produce a pattern of stripes on the retina. The intensity of the pattern is easily varied. More importantly, the pattern can be projected over different-sized retinal areas corresponding to visual fields of 0.5 to 15 degrees in diameter. The device may be useful for vision research and preoperative assessments of visual potential.

Holography↗

Glomerular deposition of complement-control proteins in acute and chronic glomerulonephritis.

Acute poststreptococcal glomerulonephritis (AGN) differed from membranoproliferative glomerulonephritis (MPGN) and lupus nephritis (SLE) in that two of the proteins that control the C3b-dependent convertase, beta 1H and the C3bC4b-inactivator cofactor (C3bC4bICo), were frequently absent from the glomerular deposits. In addition, factor B was distributed with C3 in the capillary walls in hypocomplementemic AGN patients. From this, it can be assumed that C3bBb is in the deposits, uninhibited by control proteins as would be predicted for alternative pathway activation. Factor B could not be found in normocomplementemic AGN, was rarely present in MPGN, but was usually present in SLE, most often in the mesangium. In MPGN and SLE, the control proteins were nearly always present in the glomeruli in a distribution like that of C3; IN MPGN they were particularly abundant. Complement profiles indicated an occasional transient reduction in serum C4 level early in AGN. Thus, although there is occasional evidence of early classical activation in AGN, more characteristic is a long period of alternative activation. Serum levels of control proteins did not deviate greatly from normal except for reduced serum beta 1H levels in MPGN type I.

Biopsy, Needle↗

Culture of human pituitary prolactin and growth hormone cells.

Fragments of pituitary tissue obtained from a total of 37 patients with either breast cancer, diabetic retinopathy, galactorrhea, or acromegaly were dissociated into single cell suspensions prior to cell culture. Release of human growth hormone (hGH) and human prolactin (hPRL) into the culture medium was measured by radioimmunoassay. During a 3-week culture period, prolactin cells released 9--13 times the intracellular levels of hPRL at the time of seeding, whereas hGH release from growth hormone cells was only 1--2 times that of their initial intracellular level during this same time. Both growth hormone and prolactin cells retained distinctive ultrastructural features during culture. The prolactin cells responded to TRH stimulation by elevated release of PRL into the medium. No evidence for mitotic division of prolactin cells in vitro was found.

Breast Neoplasms↗