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Biomedical subjects

J J Miller

Publications and source records attributed to J J Miller.

At least 109 records · Page 6Linked to original sources
PubMed1986

Collateral specific long term potentiation of the output of field CA3 of the hippocampus of the rat.

Long term potentiation (LTP) in response to brief high frequency trains has been reported for many pathways in the hippocampus. The mechanisms involved are still unclear. The present experiments set out to confirm reports in the literature that LTP of output from CA3 neurons can be specific to particular collaterals. Single pulses delivered to area CA3 produced field responses nearly simultaneously in area CA1 and in the lateral septum (LS). High frequency stimulation of CA3 produced long term potentiation of CA1 but not LS responses. The CA1 response to stimulation of the contralateral hippocampus did not potentiate when the CA1 response to CA3 stimulation showed long term potentiation. The CA1 and LS responses to CA3 stimulation showed similar strength-duration, strength-amplitude and frequency following characteristics. Their latencies were comparable to the latencies of antidromic activation of CA3 cells from CA1 and LS. Movement of stimulating electrodes to the region of the Schaffer collaterals increased the latency of the LS response and decreased the latency of the CA1 response but left the sum of these latencies unchanged. It was concluded that the CA3 and Schaffer stimulation were activating LS and CA1 collaterals of the same CA3 neurons. CA1 and LS responses to CA3 stimulation showed somewhat different paired pulse and frequency potentiation characteristics. These data confirm reports in the literature that long term potentiation is both input-specific and collateral-specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Unusual catheter tip placement from attempted central venous catheterization.

Percutaneous catheterization of the subclavian and internal jugular veins is rapid and has overall complication rates from 0% to 11.2%. Noncentral placement of catheter tips has been reported in 1% to 16% of all cases. Two previously unreported locations for noncentral placement of catheter tips are described.

Adult↗
PubMed1986

Psychosocial functioning of siblings of children with rheumatic disease.

The potential impact of an ill child on other siblings in the family was examined by comparing 72 siblings of children with rheumatic disease with 60 siblings of healthy children from demographically matched families. Psychosomatic, behavioral, emotional, and social problems, as reported by both the parents and the siblings, were investigated. Although siblings of patients with rheumatic disease generally were functioning as well as siblings of healthy children, they reported having more allergies and asthma. A set of vulnerability and protective factors was tested as predictors of sibling functioning. Cohesive and expressive family environments in which mothers and patients with rheumatic disease were functioning adequately promoted better adaptation among the siblings.

Adaptation, Psychological↗
PubMed1986

Different patterns of C3 and C4 activation in the varied types of juvenile arthritis.

Quantitative assays for C3 and C4 activation were carried out simultaneously on blood from children with varied types of juvenile arthritis. Factor VIII-related antigen was also measured as an indicator of vascular damage. In active systemic juvenile arthritis, the C4d/C4 ratio was frequently elevated and was usually associated with elevated C3d/C3 ratios and elevated concentrations of factor VIII-related antigen. Children with chronic polyarticular arthritis, no matter which forms of onset they had had, also had increased levels of the C4d/C4 ratio, C3d/C3 ratio, and factor VIII-related antigen, but these were less consistent and were not associated with each other. In contrast, in pauciarticular arthritis there was a uniquely isolated increase in the C3d/C3 ratio. This work implies that there are different mechanisms responsible for complement activation in the different types and at different stages of juvenile arthritis.

Adolescent↗
PubMed1986

Autoantibody profiles in juvenile arthritis.

Serologic and correlational testing was performed in a series of 65 patients diagnosed as having juvenile arthritis (JA) and in 21 age matched controls to detect the presence of antinuclear antibodies (ANA), antibodies to ssDNA, IgM and IgG rheumatoid factor (RF), immune complexes (IC) and antibodies to bovine type I and human type II collagen. ANA were found in 51% of the JA patients; the highest incidence (75%) was noted in the pauciarticular onset disease group. Low levels of anti-ssDNA antibodies were detected in 22% of the patients, all of whom had active disease. IgM RF was detected in 35% of the JA patients but only 6% of patients had IgG RF. Similarly, about one fourth of the JA patients had IC detected by the Clq assay. Antibodies to bovine type I and human type II collagen were noted in about 12% of the JA patients.

Adolescent↗
PubMed1985

Alterations of inhibitory processes in the dentate gyrus following kindling-induced epilepsy.

In vitro hippocampal slices were prepared from control and commissural-kindled rats and the inhibitory processes of the dentate granule cells were assessed using paired perforant path stimulation. An early (20 ms) Cl(-)-dependent and a late (200 ms-8 s) Cl(-)-independent inhibition were shown to be present in the dentate. Enhancement of the late Cl(-)-insensitive inhibition was observed following the establishment of commissural kindling and persisted for periods of up to eight weeks following the last seizure.

Animals↗
PubMed1985

Long-term potentiation facilitates behavioral responding to single-pulse stimulation of the perforant path.

Three experiments were conducted to determine whether long-term potentiation (LTP) could enhance the stimulus properties of electrical brain stimulation. First, a paradigm was developed in which single-pulse stimulation of the perforant path (PP) could acquire control over operant responses. Evoked potentials were recorded from the dentate gyrus (DG) on every trial in order to measure the postsynaptic consequences of the stimulus and to monitor synaptic efficacy in the PP-DG synapses. The second experiment confirmed the relation between the amount of evoked activity and acquisition rate and also showed that transecting the PP impaired performance. In the third experiment, high-frequency stimulation of the PP produced LTP and accelerated subsequent acquisition of behavioral responding to PP stimulation. These results document a clear link between increases in synaptic efficacy and changes in behavior and thereby demonstrate the ability of LTP to serve as at least one component of the neural bases of learning and memory.

Animals↗
PubMed1985

The neostriatal mosaic: compartmental distribution of calcium-binding protein and parvalbumin in the basal ganglia of the rat and monkey.

Calcium-binding protein (CaBP) and parvalbumin are two proteins that are expressed in brain and bind calcium in the micromolar range. The immunohistochemical distribution of these two proteins was examined in the basal ganglia of rats and rhesus monkeys. In the striatum, CaBP immunoreactivity is localized to a subset of striatonigral projection neurons; CaBP-positive neurons are distributed in areas containing somatostatin-immunoreactive fibers and not in the complementary areas containing dense mu opiate-receptor binding. These biochemical labels mark, respectively, the matrix and patch compartments of the striatum. Previous studies have shown that striatal matrix neurons project to the substantia nigra pars reticulata, whereas striatal patch neurons project to the substantia nigra pars compacta. Consistent with the restricted localization of CaBP in the matrix projection neurons is the confinement of CaBP-immunoreactive afferent fibers to the pars reticulata. CaBP is also localized to a portion of dopaminergic and a few nondopaminergic neurons in the substantia nigra pars compacta and in most dopaminergic neurons in the ventral tegmental area. Parvalbumin immunoreactivity is localized to a subset of substantia nigra pars reticulata neurons and their axons. In the lateral striatum, some medium-sized aspiny interneurons are also parvalbumin immunoreactive. The distinct distributions of CaBP and parvalbumin in the basal ganglia are discussed in terms of their possible roles as intracellular calcium buffer systems related to the physiologic response properties of the neurons in which they are contained.

Animals↗
PubMed1985

Levels of hippocampal calcium and zinc following kindling-induced epilepsy.

Hippocampal calcium and zinc content was determined using atomic absorption spectrophotometry in control and commissural-kindled rats. In animals exhibiting 5-10 consecutive motor seizures hippocampal calcium was slightly elevated (356.7 parts per million (ppm), dry weight) but not significantly different from controls (329.8 ppm), whereas the amount of zinc was significantly higher (101.6 ppm) than in nonstimulated animals (88.3 ppm). These results are indicative of certain pathophysiological changes in kindled hippocampi, most likely localized to the granule cells of the dentate gyrus where the bulk of hippocampal zinc is confined.

Animals↗
PubMed1985

Inhibitory processes of hippocampal CA1 pyramidal neurons following kindling-induced epilepsy in the rat.

To determine the alterations in cellular function which may contribute to the chronic predisposition of neuronal tissue to epileptiform activity, the membrane properties and inhibitory processes of hippocampal CA1 pyramidal cells were investigated using in vitro slices prepared from commissural-kindled rats. No changes were observed in resting membrane potential, input resistance, spike amplitude, and membrane time constant of "kindled" CA1 pyramidal neurons when compared with controls. There were also no differences between control and kindled preparations in the amplitude of recurrent inhibitory postsynaptic potentials (IPSP) and in the duration of inhibition produced by either alvear (Alv) or stratum radiatum (SR) stimulation. Irrespective of group, repetitive stimulation of the Alv reduced the amplitude of the recurrent IPSP but failed to induce seizurelike activity. On the other hand, repetitive stimulation of SR frequently produced a neuronal burst discharge even though the duration and to some extent the amplitude of orthodromic inhibition was increased. On the basis of these data, it may be suggested that chronic changes in CA1 pyramidal cell membrane properties and transient reductions of inhibitory processes do not underlie the enhanced sensitivity of these neurons to seizure activity associated with kindling.

Animals↗
PubMed1985

The effects of paracetamol on frusemide ototoxicity.

Paracetamol (acetaminophen) is currently one of the most widely used drugs. In large doses, paracetamol is both nephrotoxic and hepatotoxic, and this toxicity may arise through the production of free radicals. Recently, there has been a revival of interest in the hypothesis that aminoglycoside antibiotics are ototoxic because they facilitate free-radical production. Aminoglycosides interact strongly with loop diuretics, producing enhanced ototoxicity. The object of the present study was to determine whether paracetamol would also interact with a loop diuretic. Pigmented guinea pigs received a dose of 500 or 1000 mg/kg paracetamol via an intragastric cannula. Compound action potentials (CAP) were recorded every 10 min for 2 h. Paracetamol alone had no effect on CAP thresholds, but significantly enhanced the CAP decrement induced by frusemide given intraperitoneally 1 h after paracetamol. This enhancement was larger in animals receiving 1000 mg/kg paracetamol. Repetition of these drug doses in recovery experiments indicated that all threshold shifts recovered within 7 days.

Acetaminophen↗
PubMed1984

Hippocampal calcium-binding protein during commissural kindling-induced epileptogenesis: progressive decline and effects of anticonvulsants.

Changes in hippocampal calcium-binding protein (CaBP) were examined in rats given kindling stimuli via electrodes chronically implanted in the midline commissural pathway. CaBP levels decreased progressively and were significantly lower (16.6%) than controls after only 10 kindling trials. The maximum fall (33%) was achieved prior to the production of stage 5 motor seizures and additional kindling-induced seizures produced no further decline. Induction of motor seizures with pentylenetetrazol had no effect upon hippocampal CaBP levels. Diazepam treatment during the course of kindling significantly increased the number of stimulation trials required to produce stage 5 motor seizures but did not inhibit the fall in CaBP. Diazepam treatment of fully kindled rats was effective in blocking generalized motor seizures without causing any restoration of the depleted levels of CaBP. Diphenylhydantoin was neither effective during the course of kindling nor in modifying the effect of further stimulations in fully kindled rats. These data indicate that the highly specific decrease in hippocampal CaBP, previously demonstrated to be localized to dentate granule cells and their processes following kindling-induced epilepsy, does not result from the expression of full tonic-clonic (stage 5) motor seizures. The loss of CaBP may be a biochemical factor contributing either to the predisposition of neuronal tissue to seizure activity or to a protective attempt to overcome the deleterious effect of repeated high-frequency stimulation.

Animals↗