Rechargeable silver-modified mercuric oxide-zinc cell for cardiac pacemakers

Tests were conducted on rechargeable mercury-zinc pacemaker batteries under simulated and actual biologic conditions, using a variety of discharge rates and charging schedules. In tests on 96 cells at a 6.4 milliampere (ma) discharge, recharging once every 15 months of simulated pacing at a 25 microampere (mua) drain, the earliest cell failure occurred after an equivalent of 50 years of pacing. The mean pacing equivalent for all 96 cells was more than 140 years. In 6.4 ma discharge tests on 24 cells, recharging once every 8 days of simulated pacing, only 1 cell in 24 failed after an equivalent of more than 500 years of pacing (actual time 2 years). In tests on 13 cells pacing at a 200 mua drain without recharging, the simulated mean duration of pacing before total discharge was 4.8 years. Seven other cells at a 200 mua drain with periodic recharging continue to function normally after more than 7 years of actual time, simulating 56 years of pacing at a 25 mua drain. Cardiac pacemakers using the rechargeable mercury-zinc cell have been implanted in animals for more than 2 1/2 years and in patients for more than 1 year with all units continuing to function satisfactorily. It has been demonstrated unequivocally that a rechargeable mercury-zinc pacemaker will function continuously for more than 4 years without recharging and that periodic recharging will extend pacing life far beyond that predicted for lithium and nuclear primary power sources.     

The synaptic organization of the cerebello-olivary circuit

Section of the superior cerebellar peduncle just rostral to the deep cerebellar nuclei results in degenerating axon terminals within the contralateral inferior olive. The nuclear origin of this fiber system and its distribution within the subdivisions of the inferior olive were described in a companion study (Martin et al., 1976). Precise localization of these degenerating terminals within the nucleus was accomplished by the examination of 1 mu plastic sections cut from each tissue block prior to thin sectioning. Degenerating axon terminals are present in all the nuclear subdivisions and when seen with the electron microscope they frequently are localized in the previously described synaptic clusters (King, 1976). These terminals demonstrate an electron dense reaction at survival times of 2 and 3 days. By day 4, they are shrunken and irregular in shape, and typically are surrounded by astrocyte processes. Cerebello-olivary axon terminals measure 1-3 mu, contain spherical, clear synaptic vesicles and typically contact spiny appendages within the synaptic clusters (glomeruli). Thus, we have demonstrated that one of the primary axon systems which terminates within the synaptic clusters is from the cerebellar nuclei. We have yet to determine the origins of the remaining terminals within the synaptic clusters which include endings with either smaller spherical, pleomorphic or numerous dense core vesicles.     

Effects of beta-hydroxybutyrate, glycerol, and free fatty acid infusions on glucagon and epinephrine secretion in dogs during acute hypoglycemia

The importance of glucagon in the regulation of carbohydrate metabolism is clearly established. However, the role played by this hormone in the regulation of the overall fuel economy is less certain, particularly with respect to such nonglucose fuels as free fatty acids, glycerol, and ketoacids. In order to elucidate glucagon's role with respect to the latter substrates, dogs were infused with solutions of these three fuels, and their A-cell responses to concomitant insulin-induced hypoglycemia were studied. In addition, epinephrine levels were also monitored. It was found that while these infusions failed to suppress glucagon release, the ketoacid infusion did significantly reduce epinephrine secretion during the insulin-induced hypoglycemic period. It was therefore concluded that glucagon secretion under these experimental conditions is not responsive to prevailing non-glucose fuel levels. Indeed, these data suggest that the sympathetic nervous system may play an important role in the regulation of the over-all fuel economy.     

Disseminated Blastoschizomyces capitatus infection in acute myeloblastic leukaemia. Report of three cases

Three new cases of Blastoschizomyces capitatus infection occurring in neutropenic patients with acute myeloblastic leukaemia are reported. B. capitatus was isolated from blood cultures in all patients. All three patients were treated with amphotericin B, but only one was cured from the infection. Our study confirms the emergence of B. capitatus as an opportunistic agent of disseminated fungal infection in leukaemic patients.     

Quantitative brain magnetic resonance imaging in attention-deficit hyperactivity disorder

BACKGROUND: Anatomic magnetic resonance imaging (MRI) studies of attention-deficit hyperactivity disorder (ADHD) have been limited by small samples or measurement of single brain regions. Since the neuropsychological deficits in ADHD implicate a network linking basal ganglia and frontal regions, 12 subcortical and cortical regions and their symmetries were measured to determine if these structures best distinguished ADHD. METHODS: Anatomic brain MRIs for 57 boys with ADHD and 55 healthy matched controls, aged 5 to 18 years, were obtained using a 1.5-T scanner with contiguous 2-mm sections. Volumetric measures of the cerebrum, caudate nucleus, putamen, globus pallidus, amygdala, hippocampus, temporal lobe, cerebellum; a measure of prefrontal cortex; and related right-left asymmetries were examined along with midsagittal area measures of the cerebellum and corpus callosum. Interrater reliabilities were .82 or greater for all MRI measures. RESULTS: Subjects with ADHD had a 4.7% smaller total cerebral volume (P = .02). Analysis of covariance for total cerebral volume demonstrated a significant loss of normal right > left asymmetry in the caudate (P = .006), smaller right globus pallidus (P = .005), smaller right anterior frontal region (P = .02), smaller cerebellum (P = .05), and reversal of normal lateral ventricular asymmetry (P = .03) in the ADHD group. The normal age-related decrease in caudate volume was not seen, and increases in lateral ventricular volumes were significantly diminished in ADHD. CONCLUSION: This first comprehensive morphometric analysis is consistent with hypothesized dysfunction of right-sided prefrontal-striatal systems in ADHD.