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Biomedical subjects

R H Schmidt

Publications and source records attributed to R H Schmidt.

8 recordsLinked to original sources
PubMed1992

Cortical mapping and local anaesthetic resection as an aid to surgery of low and intermediate grade gliomas.

We report four cases of the use of peroperative cortical mapping during craniotomy under local anaesthesia to define the relationship between the glioma and speech and somatosensory cortex. This enabled a radical subtotal (two cases) or an apparent total (two cases) excision of the tumour close to the somatosensory and speech cortex with no permanent neurological deficit. Use of this technique allows radical excision of intrinsic low and intermediate grade gliomas that would otherwise be considered unexcisable and may lead to an improved survival.

Adult↗
PubMed1992

Acute cauda equina syndrome from a ruptured aneurysm in the sacral canal. Case report.

The case is presented of a young woman with acute cauda equina syndrome from a ruptured aneurysm in the sacral canal. The lesion was associated with pathological enlargement of the lateral sacral arteries bilaterally, which presumably occurred to provide cross-pelvic collateral flow in response to the diversion of the right internal iliac artery for renal transplantation. The patient presented with signs and symptoms of spontaneous spinal epidural hemorrhage. The radiographic features of this lesion are described. In addition to angiography and partial embolization of the vascular supply, contrast-enhanced high-resolution computerized tomography was essential in the diagnosis and treatment of this unique aneurysm.

Acute Disease↗
PubMed1979

Distribution of hypertrophied locus coeruleus projection to adult cerebellum after neonatal 6-hydroxydopamine.

Following treatment as neonates with a high subcutaneous dose of 6-hydroxydopamine (6-OHDA), the projections of the locus coeruleus were mapped in the brains of adult rats. This was done using the technique of unilateral lesions in the nucleus followed by simultaneous determinations of norepinephrine (NE) levels, dopamine-beta-hydroxylase (DBH) activity and synaptosomal [3H]NE uptake in various terminal areas. In particular the cerebellum was subdivided into 3 areas in order to assess any changes from normal in the distribution of the hypertrophied noradrenergic projections here. In vehicle-control rats the lesions resulted in an 80--85% loss of NE in the parietal cortex ipsilateral to the lesion and a 15--20% loss contralaterally. In the control cerebellum the locus coeruleus projection, based upon changes in all 3 markers, is distributed 2/3 ipsilaterally and 1/3 contralaterally with the same pattern present in all 3 subregions. The neonatal 6-OHDA treatment resulted in virtually complete loss of noradrenergic terminals in the cerebral cortex. Following neonatal 6-OHDA treatment cerebellar levels of NE, DBH and [3H]NE uptake increased by between 20--60%, with the smallest increases occurring in [3H]NE uptake. In these rats the locus coeruleus accounted for at least 75--80% of the cerebellar noradrenergic parameters. Unlike control rats however, the lesions in these rats produced only ipsilateral decreases in NE and DBH. On the other hand changes in [3H]NE uptake indicated a normal 2/3 ipsilateral, 1/3 contralateral pattern. It is suggested that two separable events occur in the noradrenergic projection to the cerebellum. The first is the regeneration of an increased number of nerve terminals, or sprouting, and the second is a build-up of synaptic vesicles, or collateral accumulation. The sprouting, judging from the [3H]NE uptake data, occurs with apparently normal distribution, but the accumulation of NE and DBH is confined predominantly to the ipsilaterally projecting axon terminals. This may be the consequence of collateral accumulation resulting from the degeneration of the largely ipsilateral coeruleocortical projection.

Animals↗
PubMed1979

Regional development of norepinephrine, dopamine-beta-hydroxylase and tyrosine hydroxylase in the rat brain subsequent to neonatal treatment with subcutaneous 6-hydroxydopamine.

Neonatal rats were injected subcutaneously with 100 mg/kg 6-hydroxydopamine (6-OHDA), or vehicle, on postnatal days 1, 2 and 3. At several times thereafter, determinations of tyrosine hydroxylase (TOH) and dopamine-beta-hydroxylase (DBH) activities, and norepinephrine (NE) concentration were made in the parietal cortex, cerebellum and pons-medulla in order to assess the extent of initial noradrenergic degeneration induced, and the rate of any ensuing regeneration. By the day following completion of the treatment (postnatal day 4), degeneration of noradrenergic terminals in the parietal cortex and cerebellum was very extensive, with NE levels and DBH activities reduced by more than 80%, and TOH activities reduced by 50%. In the parietal cortex noradrenergic degeneration remained virtually complete; and 9 and 70 days postnatal NE concentration and DBH and TOH activities were all decreased by more than 90--95%. In the cerebellum a progressive regeneration and apparent sprouting of NE fibers was observed. By postnatal day 9, NE, DBH and TOH in this tissue had all recovered to near control levels, and by day 70 these measures exceeded control levels by 95%, 115% and 50% respectively. In the pons-medulla, the initial effect of 6-OHDA on any of the measured parameters was negligible. By postnatal day 9 an increase in NE concentration was apparent, which increased further by day 70 to surpass the control level by 70%. At this same time DBH activity was increased by only 15% and TOH activity was unchanged. Separate analysis of the rostral half of the pons, which contains the locus coeruleus, revealed that on day 70 NE and DBH levels were increased much more substantially than in the whole pons-medulla, and TOH activity was also significantly elevated. This data indicates that the initial amount of degeneration induced by the 6-OHDA treatment is similar in both the parietal cortex and cerebellum, but regeneration proceeds only in the cerebellum. This suggests that noradrenergic fiber growth and regeneration in each target tissue is under independent regulation, possibly by the individual target neurons themselves.

Animals↗
PubMed1979

Assessment of the effects of neonatal subcutaneous 6-hydroxydopamine on noradrenergic and dopaminergic innervation of the cerebral cortex.

Female rats, treated at birth with 6-hydroxydopamine (3 x 100 mg/kg s.c. at 24 h intervals) or vehicle, were subjected at 112 days of age to unilateral electrolytic lesions of the locus coeruleus. Two weeks later regions of the telencephalon, both ipsi- and contralateral to the lesion, were simultaneously assayed for norepinephrine (NE) and dopamine (DA) content, and for tyrosine hydroxylase (TOH) and dopamine-beta-hydroxylase (DBH) activities. In the vehicle-treated rats the lesion resulted in at least an 80% reduction of NE and DBH on the ipsilateral side, relative to the contralateral side. TOH was reduced to a similar extent only in the parietal cortex and hippocampus. In the prefrontal cortex and cingulate gyrus TOH was decreased by only 31% and 64% respectively; the remainder was interpreted to be associated with projections of the mesocortical dopamine system. From this data it was possible to calculate that the ratio of TOH to DA in dopaminergic terminals is about 10-fold greater than the ratio of TOH to NE in noradrenergic terminals. Neonatal 6-hydroxydopamine treatment resulted in practically total elimination of noradrenergic terminals throughout the telencephalon, and the locus coeruleus lesion had no additional effect. The drug treatment produced no significant change in DA content or in the TOH to DA ratio in the prefrontal cortex and cingulate gyrus, indicating complete sparing of the mesocortical DA projections.

Animals↗
PubMed1977

Species differences and effect of incubation time on lactic streptococcal intracellular proteolytic enzyme activity.

Ruptured cells of Streptococcus lactis C2, S. cremoris ML 1 and a lactose-negative proteinase-negative (Lac-Prt-) mutant of S. lactis C2 (LMO220) were fractionated into the soluble, particulate, and ribosome fractions by differential centrifugation. S. lactis C2 possessed higher activity of intracellular proteinase, alanylglycinase, particulate associated dipeptidase and ribosome associated dipeptidase and ribosome associated dipeptidase than did S. cremoris ML1. LMO220 was lower in intracellular proteinase and dipeptidase activity and lower in ribosome associated dipeptidase activity than was the parent strain C2. Particulate associated dipeptidase activity was substantially higher in the mutant cells. Extending incubation times from 5 to 24 and 32 h reduced intracellular proteinase and ribosome associated dipeptidase activity in S. lactis C2 and S. cremoris ML1. Soluble alanylglycinase activity and particulate associated dipeptidase activity of ML1 were reduced drastically after 24-h incubation.

Dipeptidases↗