Biomedical subjects
A Hill
Publications and source records attributed to A Hill.
Right place, right time.
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Score on quality.
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A testing question.
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Needs assessment made simple.
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Serum sodium concentration and intraventricular hemorrhage in premature infants.
Recent data suggest that early loss of brain tissue water content, ie, decreased extravascular cerebral tissue pressure, may play a role in the pathogenesis of germinal matrix/intraventricular hemorrhage in the premature newborn. This study examines the relationship between the concentration of serum sodium and germinal matrix/intraventricular hemorrhage in 299 premature infants with birth weights of less than 1500 g during the first 4 days of life. Intraventricular hemorrhage developed in 34 (32%) of the 106 infants with maximum serum sodium levels of 145 mmol/L or less and in 54 (28%) of 193 infants whose highest serum sodium levels were greater than 145 mmol/L (chi 2 = 0.37). These data suggest that concentrations of serum sodium greater than 145 mmol/L are not associated with an increased risk of germinal matrix/intraventricular hemorrhage in the premature newborn. Consequently, more liberal administration of fluids to maintain extravascular cerebral tissue pressure is unlikely to reduce the incidence of germinal matrix hemorrhage/intraventricular hemorrhage.
The effect of electrode position on flash visual evoked potentials in the newborn.
We examined how changes in electrode position affected the visual evoked potential in 74 high-risk newborns using a multiple electrode technique. The variation in the visual evoked potential across the occiput was documented. Visual evoked potentials that were visible at one occipital electrode position were absent at a different electrode position in 21 of 87 recordings (24%). Changes of greater than 20 msec between electrodes in latency of waves P1 or N2 occurred in 34% and 29% of recordings, respectively. The amplitude of response varied by a factor of 2.36 between mid occipital and lateral occipital electrodes. The results demonstrated that large changes in morphologic characteristics, latency, and amplitude in the visual evoked potential of the newborn result from small changes in the position of recording electrodes. These findings underscored the importance of electrode position and accurate electrode placement. Our observations also indicated that recordings from a single electrode are inadequate in providing an accurate representation of the neonatal visual evoked potential.
Implantable rate-responsive counterpulsation assist system.
To apply the potential energy source available from skeletal muscle in cardiac assistance, we developed an implantable counterpulsation assist system. This study reports the results using this implantable counterpulsation assist system in an acute in vivo animal model. Twelve dogs had a dual-chambered, extraaortic counter-pulsation pump anastomosed in parallel to the thoracic aorta. The left latissimus dorsi muscle was used to power the pump. A newly developed implantable stimulator was used to make the muscle contract in synchrony with the diastolic phase. The unique feature of this stimulator is its ability to adjust timing of muscle contraction according to changing heart rates. The stimulator is also able to detect arrhythmias, and as a safety measure, shuts down until a normal rhythm is resumed. During counterpulsation assist with the implantable counterpulsation assist system, diastolic pressure increased an average of 34 mm Hg from baseline, equivalent to a 69% augmentation. Systolic peak pressure decreased an average of 10 mm Hg, equivalent to an 11% unloading. With induced heart rate changes, the implantable counterpulsation assist system readjusted its timing, maintaining optimal counterpulsation without systolic interference. Induced ventricular tachycardia resulted in immediate shutdown of the stimulator until resumption of a normal rhythm. The feasibility of using an intraaortic balloon pump console as back-up was also demonstrated. Excellent counterpulsation was obtained with either muscle power or balloon pump console. We conclude that the implantable counterpulsation assist system can provide effective counterpulsation assist and has the potential for continuous cardiac support.
Possible relationship between chromosome alterations and in vitro cellular radiosensitivity of human malignant melanoma.
In the present study, in vitro radiation survival analysis was performed on 8 human malignant melanoma cell lines with defined karyotypes. Exponentially growing cells were irradiated to doses of 0 to 8 Gy and examined for soft agar clonogenicity. Two groups emerged from this analysis: 4 cell lines with a small shoulder (extrapolation number, n less than 2) and 4 cell lines with a large shoulder (n greater than 2). Of possible significance, 4/4 cell lines with extrapolation numbers greater than 2 demonstrated clonal structural abnormalities of chromosome 7. In contrast, 3/4 cell lines with extrapolation numbers less than 2 had no structural abnormalities of chromosome 7. These very preliminary results suggest that structural alterations of chromosome 7 may be associated with melanoma tumors with high extrapolation numbers.
Comparison of pain perceptions among males and females.
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Thalamic hemorrhage with intraventricular hemorrhage in the full-term newborn.
Intraventricular hemorrhage is an uncommon problem in the full-term newborn. In a review of 19 full-term infants with intraventricular hemorrhage diagnosed on computed tomography prior to 1 month of age, thalamic hemorrhage associated with the intraventricular hemorrhage was documented in 12 infants. Thus, thalamic hemorrhage appears to the most common source of intraventricular hemorrhage in this age group, particularly in infants who had uneventful birth histories and in whom clinical abnormalities (signs of increased intracranial pressure, seizures, altered level of consciousness) developed after the first week of life. The majority of these infants had predisposing factors for cerebral venous infarction such as sepsis, cyanotic congenital heart disease, and coagulopathy. The clinical appearance and outcome for infants with thalamic hemorrhage/intraventricular hemorrhage were similar to those in infants with intraventricular hemorrhage originating from other sites, except for an increased incidence of cerebral palsy in infants with thalamic hemorrhage/intraventricular hemorrhage. Definitive diagnosis was made on the basis of characteristic radiologic abnormalities.
The microsomal glucose-6-phosphatase enzyme of human gall-bladder.
Microsomes isolated from adult human gall-bladders have for the first time been shown to contain specific glucose-6-phosphatase activity. The gall-bladder glucose-6-phosphatase enzyme has the same molecular weight (36,500 daltons) and similar immunological properties and kinetic characteristics to the hepatic microsomal glucose-6-phosphatase enzyme.
Peritoneovenous shunts palliate malignant ascites.
Fifty-five peritoneovenous shunts (PVS) were implanted in 45 patients (29 LeVeen and 26 Denver shunts). Seventy-five percent of patients experienced relief of symptoms referable to their ascites. The mean survival time post-shunt placement was 33 weeks; however, considerable variation was noted in survival times for the various tumor types (pancreas 7 weeks, ovary 71 weeks). Significant alterations in coagulation parameters consistent with subclinical disseminated intervascular coagulation (DIC) were present in all patients with functioning shunts. These coagulation changes have proven reliable indicators of shunt patency. Shunt revision was necessary in 18 percent of patients. No significant difference in shunt patency was detected when Denver and LeVeen shunts were compared. This experience indicates that PVS offers effective palliation without undue morbidity for malignant ascites. The best results can be expected in those patients with ovarian and breast primary tumors. Because of the short time from onset of disabling ascites until death, PVS is not indicated in the majority of patients with pancreatic cancer.
The structure of a primitive kinetochore.
The isolation of yeast centromeres has provided the opportunity to describe the molecular structure of chromosome attachments to the mitotic spindle. Nucleolytic probes of chromatin structure and construction of conditional mutants in centromere function have been used to study the regulation and assembly of centromeres throughout the cell cycle in Saccharomyces cerevisiae.
Pushing the limits of recovery: hypnotherapy with a stroke patient.
Hypnotherapy was used to assist recovery of left arm function following stroke in a 66-year-old woman. Treatment protocol is described, and results are discussed in terms of how hypnosis may facilitate voluntary motor movement. Recent literature on cortical changes in hypnosis and motor improvement during hypnosis is discussed in relation to the present results.
The community development in health project.
This paper describes the purpose and process of a 15 month project established to develop resources to assist people who are seeking to use a community development approach in addressing health issues.
Acquisition and processing of a conditional dicentric chromosome in Saccharomyces cerevisiae.
The introduction of a conditional centromere into chromosome III of Saccharomyces cerevisiae provided an opportunity to evaluate phenotypic and karyotypic consequences in cells harboring dicentric chromosomes upon entry into mitosis. A mitotic pause ensued, and monocentric derivatives of chromosome III were generated at a high frequency.