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Biomedical subjects

H V Rizzoli

Publications and source records attributed to H V Rizzoli.

At least 37 records · Page 2Linked to original sources
PubMed1979

The effects of ischemia on long-tract neural conduction in the spinal cord.

In this experiment, the effects of ischemia on neural conduction in the monkey spinal cord were studied. In six monkeys generalized ischemia of the spinal cord was created by bleeding the animals to a hypotensive level below the lower limits of autoregulation in the spinal cord. The progressive development of spinal cord ischemia was documented by blood-flow measurement using the hydrogen clearance method. Physiological integrity of the spinal cord was monitored and recorded by the spinal evoked response. The spinal evoked response did not disappear until at least 10 minutes of profound ischemia. At levels of ischemia 20% to 25% of normal blood flow, the spinal evoked response was unchanged. It is concluded that long-tract neural conduction in the spinal cord is relatively resistant to the effects of ischemia.

Animals↗
PubMed1979

Experimental acute balloon compression of the spinal cord. Factors affecting disappearance and return of the spinal evoked response.

Acute balloon compression of the thoracic spinal cord for 15, 7, 5, 3, and 1 minute in monkeys caused immediate disappearance of the spinal evoked response and complete focal ischemia of the compressed segment in all animals. Only the animals in the 1-minute group, however, demonstrated return of the evoked response. These data, coupled with data from previous experiments of slow balloon compression of the spinal cord and spinal cord ischemia, suggest that the major pathological substrate for neural dysfunction after balloon compression of the spinal cord, be it acute or slow, is physical injury of the neural membrane, irrespective of blood flow changes. These findings also suggest that the ability of that membrane to recover is related to rapidity and length of time of compression. Focal changes in blood flow do not appear to be significant in this mechanism.

Acute Disease↗
PubMed1978

The effect of sciatic nerve stimulation on spinal cord blood flow.

Focal spinal cord blood flow was measured in the left dorsal column during left sciatic nerve stimulation, and compared to blood flow in the same area during sciatic nerve inactivity. Blood flow was found to be significantly increased during stimulation. It is suggested that this increased blood flow is a reflection of increased metabolic demands of the neurons and synaptic systems within the internuncial neural pools, activated by stimulation of all components of the sciatic nerve, rather than a reflection of increased non-synaptic axonal conduction in the dorsal column.

Animals↗
PubMed1977

Soluble membrane antigens of brain tumors. I. Controlled testing for cell-mediated immune responses in a long surviving glioblastoma multiforme patient.

A patient with glioblastoma multiforme survived 18 years after diagnosis and underwent 20 operations for extracranial metastasis. An immunologic survey of the patient was made over a 1-year-period using in vitro tests of lymphocyte responsiveness and skin tests with control and tumor antigens isolated from autologous and allogenic brain cell membranes. Two tissue-associated soluble cell membrane antigens also present in normal white matter, and two tumor-associated antigens (TAA) produce cell-mediated immune responses in patients with brain tumors. One of these tumor-associated antigens predominates in meningioma cells. In addition some low molecular weight components appeared, which seemed to be unique for the glioblastoma cells from the long-surviving patient.

Antigens↗
PubMed1977

Blood flow in peripheral nerves. Normal and post severance flow rates.

Regional blood flow has been measured in the sciatic nerve of cats utilizing the method of hydrogen polarography. The mean baseline flow of the sciatic nerve in cats was found to be 43 ml/100 g/min +/- 1.6 SD. Flow rates were somewhat erratic in both the proximal and distal segments of the nerve following nerve severance. The erratic flows were observed over the first 30 min following nerve cutting and by 1 hr had essentially stabilized at approximately the pre-severance flow level.

Animals↗
PubMed1977

Absence of autoregulation in peripheral nerve blood flow.

Blood flow was measured in the sciatic nerve of cats utilizing the method of hydrogen polarography. The mean baseline blood flow for all animals was found to be 47.1 ml/100 g/min +/- 14.9 SD. The flow changes produced by lowering the blood pressure by exsanguination and elevation by the use of angiotensin were then evaluated. The highest (normal) levels of blood flow were observed between the mean blood pressures of 80-110 mm Hg. At mean systemic arterial pressures of less than 85, there was a marked decrease in peripheral nerve blood flow with no detectable flow being measured below mean systemic pressures of 50 mm Hg. Above 105 mm Hg mean arterial pressure, there was a very gradual and progressive decline in blood flow to the levels measured at 200 mm Hg. These findings indicate a complete absence of vascular autoregulation in the peripheral nerve trunks.

Animals↗
PubMed1977

The effect of alpha adrenergic blockade on spinal cord autoregulation in the monkey.

Spinal cord blood flow (SCBF) was measured over a wide range of artificially varied mean systemic arterial blood pressures (MAP) in a group of monkeys with alpha adrenergic receptors blocked by the intravenous administration of phenoxybenzamine (Dibenzyline). The SCBF was found to vary linearly with changes in MAP. Autoregulation appeared to have been abolished. These data are cited as evidence for a dominant role of the sympathetic nervous system in control of the spinal circulation.

Animals↗
PubMed1977

The effects of beta adrenergic blockade on spinal cord autoregulation in the monkey.

Blood flow in the spinal cord was measured in a group of monkeys over a wide range of artificially varied blood pressures after the administration of propranolol, a beta adrenergic blocker. Spinal cord blood flow was found to be constant and in the normal range between a mean system arterial blood pressure of 50 to 150 mm Hg. From 150 to 180 mm Hg spinal cord blood flow decreased. There was no breakthrough of autoregulation, previously seen in the untreated animal. It is suggested, therefore, that the previously observed breakthrough of autoregulation is a beta adrenergic-mediated phenomenon.

Adrenergic beta-Antagonists↗
PubMed1977

Regional cerebral blood flow with intracranial mass lesions. Part I: Local alterations in cerebral blood flow.

Focal changes in the cat cerebral blood flow were studied by the technique of H2 polarography. Areas studied included the caudate nuclei, thalami and midbrain. A unilateral mass effect was created by inflation of an epidural balloon. A rapid decrease in regional cerebral blood flow was noted ipsilateral to the mass at very small balloon volumes. This was followed closely by contralateral supratentorial decrease in regional cerebral blood flow. The normal midbrain blood flow was found to be preserved until total decompensation (herniation) occurred.

Animals↗
PubMed1977

Regional cerebral blood flow with intracranial mass lesions. Part II: Autoregulation in localized mass lesion.

Autoregulation of regional cerebral blood flow was evaluated in cats. In normal baseline situations autoregulation was invariably present. Concomitant to an enlarging mass, supratentorial loss of this protective mechanism was seen both ipsilateral and contralateral to the mass. There was relative preservation of midbrain autoregulation until very high balloon volumes were reached. There was no acute regulation upon balloon deflation.

Animals↗
PubMed1976

Spinal cord blood flow as affected by changes in systemic arterial blood pressure.

The authors used the hydrogen clearance method to measure focal spinal cord blood flow (SCBF) in the rhesus monkey over a wide range of mean arterial blood pressures (MAP) in an attempt to test the hypothesis of autoregulation. The MAP was either lowered by bleeding or raised by the intravenous infusion of norepinephrine or angiotensin. The SCBF remained constant and in the normal range with an MAP of 50 to 135 mm Hg, indicating the presence of autoregulation. Below 50 mm Hg, SCBF fell passively with further decreases in MAP. At MAP values above 135 mm Hg, vasodilatation occurred which resulted in a breakthrough of autoregulation and marked increases in SCBF with further increases in the MAP.

Animals↗
PubMed1976

Preserved autoregulation in the rhesus spinal cord after high cervical cord section.

The authors studied the effect of high cervical cord section on the phenomenon of autoregulation in the rhesus monkey with the hydrogen clearance method to measure focal spinal cord blood flow (SCBF). Laminectomies were performed at T7-11 and C1-2. The spinal cord was completely severed at C1-2. Under normocapnic conditions, SCBF was then measured in the thoracic spinal cord over a wide range of blood pressures (MAP). The MAP was either lowered by bleeding or raised by the intravenous infusion of angiotensin. Autoregulation was found to be intact between 50 and 125 mm Hg, following a pattern similar to the one observed in the intact animal.

Animals↗
PubMed1976

The effect of antihistamines on experimental posttraumatic edema of the spinal cord.

The present experiments were designed to test the effect of antihistamines on the formation of post-traumatic edema of the spinal cord. Ten rhesus monkeys received 600 gm cm injuries to the T10 level of the spinal cord. Five animals received antihistamine treatment and five animals acted as untreated controls. Posttraumatic edema was estimated using radio-active tagged serum albumin. A significant increase in radioactivity of the injured segment was demonstrated in both groups when compared to noninjured issue, but no difference was demonstrated in the radioactivity of the injured segment in the treated versus the nontreated group.

Animals↗