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Biomedical subjects

M Medina

Publications and source records attributed to M Medina.

At least 181 records · Page 10Linked to original sources
PubMed1989

Unenhanced and gadolinium-DTPA-enhanced MR imaging in postoperative evaluation in pediatric brain tumors.

Gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) is a chelated paramagnetic contrast agent under clinical trial for use in magnetic resonance (MR) imaging. The increased signal intensity following the intravenous infusion of contrast medium may improve the ability of MR imaging to delineate tumors. The use of this method in 15 pediatric patients with suspected brain-tumor recurrence was analyzed. All 15 patients underwent postoperative Gd-DTPA-enhanced MR imaging, and residual tumor was demonstrated in nine of them. Based on the findings of the enhanced MR studies, four patients had additional surgery, two underwent radiation therapy, and one was given immunotherapy. Continued surveillance was recommended for the remaining eight patients. In all cases the enhanced MR imaging studies were superior to the unenhanced studies in regard to the qualitative and quantitative assessment of the residual tumor. Gadolinium-DTPA-enhanced MR imaging appears to be a safe and effective means of providing an accurate postoperative assessment of residual disease in pediatric brain-tumor patients. It is as effective as contrast-enhanced computerized tomography and has the sensitivity and anatomic resolution provided by MR imaging. The most useful role of this agent was in the postoperative period, in assessing the adequacy of surgical resection. This technique is recommended as the procedure of choice in the postoperative assessment and long-term surveillance of patients with brain tumors.

Adolescent↗
PubMed1989

An aspartic proteinase in Drosophila: maternal origin and yolk localization.

An aspartic proteinase activity has been found in Drosophila oocytes and embryos. The proteinase is maximally active at pH 3.5 and has been characterized by its sensitivity to specific inhibitors and by the specificity of cleavage. The activity is very low and has been localized in the yolk granules. The proteinase is detected in mature oocytes (i.e., it is of maternal origin) and remains essentially constant during embryogenesis. This suggests that the Drosophila aspartic proteinase functions mainly before embryogenesis.

Animals↗
PubMed1989

The contents of proteins, carbohydrates, lipids and DNA during the embryogenesis of Drosophila.

The concentration of proteins, sugars, lipids and DNA has been determined during the embryogenesis of Drosophila. The protein content decreases after fertilization, being in the late embryo only 60% the value of the oocyte. The total sugar increases about 2.5-fold, from 3.5 h on until the end of embryogenesis. The lipids increase with a sharp peak at about 4 h and decrease during the rest of embryogenesis. DNA increases exponentially from the beginning of embryogenesis.

Animals↗
PubMed1989

Expression of cytoskeletal proteins in glial cells of dorsal root ganglia.

The localization of S-100 protein-, glial fibrillary acidic protein- and vimentin-like immunoreactivity has been studied in dorsal root ganglia of the rat using monoclonal antibodies. A positive reaction for both S-100 protein-like and vimentin-like was found in satellite and Schwann cells. In addition, some large and intermediate sized neurons also result S-100 protein-like immunoreactivity. No positive reaction for glial fibrillary acidic protein-like was observed. The authors discuss these results.

Animals↗
PubMed1989

[Neurologic disorders in children with chronic terminal renal insufficiency].

Neurological alterations are very frequent in children with end stage renal disease (ESRD). In order to assess the type of these complications, a neurological study was undertaken in 30 children with ESRD. Three of the patients had convulsions and hyperreflexia was the only clinical sign found in all the patients. Low serum levels of hemoglobin and calcium and high concentrations of phosphates, aluminum and parathyroid hormone were found in all cases, but correlations with any neurological alteration were not made. Abnormal EEG with slow waves in the occipital region were obtained in 23 patients. Sensorial hypoacusia was registered in 6 children who were previously treated with aminoglucosides. The cerebral tomography showed calcifications in three instances, but only in one patient were of clinical significance. In five, out of the 30 patients, cerebral atrophy was detected. In conclusion, assessment of the neurological condition is mandatory in children with ESRD before renal transplantation is performed, since the complication itself or the therapy may interfere with rehabilitation.

Adolescent↗
PubMed1988

Cerebral scintigraphy with 111indium oxine-labelled leukocytes in the differential diagnosis of intracerebral cystic lesions.

CT scanning and scintigraphy with 111Indium-oxide-labelled white blood cells were used to study 32 cases of intracerebral cystic lesions. The results and the criteria of positivity used to lower the false positive rate are discussed. A new criterion, designed to assess the time course of the scintiscan and so reduce still further the frequency of false positives is put forward.

Adolescent↗
PubMed1988

Neuralgia of the intermediate nerve combined with trigeminal neuralgia: case report.

An unusual case of a combination of trigeminal and intermediate nerve neuralgia is presented, caused by vascular compression of both of the nerve roots by different vessels. Because the neuralgia of the intermediate nerve could be cured by a vascular decompression operation, it is suggested to include it among the hyperactive dysfunction syndromes of cranial nerves caused by vascular compression at the root entry zone of the nerves. Therefore also for treatment of this neuralgia the non-destructive vascular decompression operation should be taken into consideration.

Cerebrovascular Disorders↗
PubMed1988

Drosophila cathepsin B-like proteinase: a suggested role in yolk degradation.

A cysteine, cathepsin B-like proteinase activity has been found in Drosophila embryos. It appears associated with yolk granules and its activity during embryogenesis correlates well with the degradation of these organelles. In mature oocytes, the enzyme is found in an inactive form which may be activated by limited proteolysis by a serine proteinase also present in oocytes. In early embryos, when solubilized in vitro, the cathepsin B-like proteinase is found in a form of high molecular mass (approx 1000 kDa). This decreases with development down to about 39 kDa, likely the mass of the free proteinase. The heavy form apparently results from the tight association with a yolk protein complex. The proteinase has been found in vitro to degrade readily the yolk polypeptides. The proteinase activity increases during early embryogenesis in parallel with the decrease in molecular weight of the heavy form, and decreases to low values in late embryos. We have also found that ammonium chloride can inhibit in vivo the degradation of yolk and, in parallel, the developmental inactivation of the proteinase. The results altogether suggest that the cathepsin B-like proteinase is implicated in yolk degradation in Drosophila.

Ammonium Chloride↗
PubMed1988

Influence of lactic starter inoculation, curd heating and ripening temperature on Staphylococcus aureus behaviour in Manchego cheese.

Growth and survival of Staphylococcus aureus were investigated in 52 lots of raw ewe's milk Manchego cheese manufactured and ripened under different conditions. A 5.8-fold reduction in S. aureus counts after 60 days of ripening was obtained by inoculating milk with 1% Streptococcus lactis culture, and a further 2.0-fold reduction could be achieved by adding 0.1% Lactobacillus plantarum culture. Curd heating temperature had a significant effect on S. aureus survival, with counts 4-5 times lower in cheese from 30 degrees C curd than in cheese from curd heated at 36-40 degrees C. Ripening temperature was the parameter with the greatest influence on S. aureus counts, which reached in cheese cured at 10 degrees C or 20 degrees C for 60 days levels 10 and 100 times lower, respectively, than in cheese held at 5 degrees C.

Cheese↗
PubMed1988

Staphylococcus aureus, thermostable nuclease and staphylococcal enterotoxins in raw ewes' milk Manchego cheese.

Growth and survival of two enterotoxigenic strains of Staphylococcus aureus were studied during manufacture and ripening of eight batches of raw ewes' milk Manchego cheese. Only 2-3 generations of Staph. aureus occurred in the vat and during pressing. The death rate of Staph. aureus (mean decrease in log cfu/g/week of ripening) from day 1 to day 60 was 0.421 in cheese made with 1% Streptococcus lactis starter and 0.404 in cheese made without starter. Thermostable nuclease was produced in the vat by growing Staph. aureus cells; it was inactivated by rennet during the first 24 h and synthesized again by surviving cells of Staph. aureus from day 1 to day 60. Staphylococcal enterotoxins A, B, C and D were not detected in any batches of cheese, even though Staph. aureus counts exceeded 10(7) cfu/g.

Animals↗
PubMed1988

A quantitative study of enterotoxin production by sheep milk staphylococci.

Of 124 staphylococcal strains isolated from sheep milk, 78 produced enterotoxin A, B, C, or D when evaluated by an enzyme-linked immunosorbent assay. Enterotoxins A and D, elaborated by 44 and 43 strains, respectively, showed the highest incidence. Enterotoxin production by coagulase-negative strains (one Staphylococcus cohnii, three S. epidermidis, five S. haemolyticus, and four S. xylosus) was detected. Linear and logarithmic-logarithmic regressions of optical density on enterotoxin concentration yielded the best-fitting equations for enterotoxin quantitation. A significantly higher incidence of enterotoxin producers and significantly higher levels of enterotoxins produced were recorded for coagulase-positive, thermostable nuclease-positive, hemolysis-positive, or mannitol-positive strains. Mannitol utilization was the best test for discriminating between enterotoxigenic and nonenterotoxigenic staphylococci.

Animals↗
PubMed1988

Gd-DTPA-enhanced MR imaging in pediatric patients after brain tumor resection.

A prospective study was conducted in 15 pediatric patients who had undergone resection of intracranial tumors. The object of the study was to determine the safety and efficacy of magnetic resonance (MR) imaging performed after the administration of gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) in evaluating residual or recurrent tumor. Precontrast T1-weighted, intermediate, and T2-weighted images were obtained at a field strength of 1.5 T. Gd-DTPA was then injected intravenously in a dose of 0.1 mmol per kilogram of body weight. T1-weighted images were obtained within 5 minutes after the injection, intermediate and T2-weighted images were obtained 10 minutes after the injection, and T1-weighted images were obtained approximately 20 minutes after the injection. None of the patients experienced allergic reactions or other side effects. Physical examination findings and laboratory values were unchanged after the Gd-DTPA-enhanced examination. In six patients, contrast-enhanced images depicted tumor not suspected on nonenhanced images. In four other patients, enhanced images provided better definition of the tumor core. The images of one patient with a brain stem tumor showed no evidence of enhancement. Pre- and postcontrast images of three previously treated patients showed no evidence of tumor. Gd-DTPA appears to be a safe and effective contrast agent for MR imaging and provides a more accurate method of imaging in the follow-up of brain tumors in pediatric patients.

Brain↗
PubMed1988

Amyloidoma of the cervical spine: a case report.

This is the first published report of an amyloidoma localized to the cervical spine. Primary amyloidosis of bone is rare. Only 5 cases involving the spine have been described. We present a 74-year-old man with cervical and occipital radicular pain as the manifestations of an amyloidoma involving the 2nd cervical vertebra. The signs and symptoms of this disease, when localized to the vertebrae, are nonspecific and result from bony destruction and compression of neural structures. Diagnosis requires a high index of suspicion and, ultimately, adequate tissue biopsy for histopathological studies. Curative resection is possible for well-localized lesions. Additionally, external immobilization with a halo vest and bony grafting for fusion may be indicated when the cervical spine is involved.

Aged↗
PubMed1987

Long-acting bromocriptine for the acute treatment of large macroprolactinomas.

Six patients with hyperprolactinemia, visual impairment and large macroprolactinoma were treated with a long-acting bromocriptine, in dosage of 50 mg as a single im injection. All patients underwent a full assessment of pituitary prolactin (PRL) secretion before treatment and the studies were repeated about every week during 40 days. Following bromocriptine injection a rapid amelioration of the clinical and visual defects occurred in all patients. Likewise, a significant reduction of the hyperprolactinemia was documented in all six patients and in three of them serum PRL levels reached values as low as 20 ng/ml, and a tumor size reduction was demonstrated by cranial computerized tomography in three of the six cases. No side effects were associated with the administration of bromocriptine. From this study we conclude that the long-acting bromocriptine represents an additional option for the initial management of large prolactinomas in particular when they are associated with severe visual impairment.

Bromocriptine↗
PubMed1987

Chronic extradural hematomas of the posterior cranial fossa.

During the past 6 years, seven patients with chronic extradural hematomas have been observed at these hospitals. All had a history of occipital injury. Occipital fracture was demonstrated in five cases (by skull x-ray in three cases, at operation in two). The diagnosis was obtained by computed tomography scan in six cases and by iodoventriculography in one. One patient had an associated cerebral lesion, namely, a contralateral temporoparietal contusion. The interval between injury and operation ranged from 27 to 13 days with a mean of 19 days. Only one patient was not operated on, because he was free from symptoms and the hematoma was small. The course was excellent in all seven cases.

Adolescent↗
PubMed1987

Enterobacteriaceae, coliforms, faecal coliforms and salmonellas in raw ewes' milk.

Thirty-nine samples of freshly drawn ewes' milk collected at 13 farms, and 120 samples of raw ewes' milk collected on arrival at a dairy were examined. Farm samples had geometric mean counts of 4.4 X 10(2) Enterobacteriaceae/ml, 3.9 X 10(2) coliforms/ml and 2.0 X 10(2) faecal coliforms/ml, whereas the respective mean counts were 6.2 X 10(3)/ml, 5.4 X 10(3)/ml and 1.3 X 10(3)/ml for dairy samples. Salmonellas were not detected by enrichment procedures in any of the 159 samples examined. Escherichia coli (47.5% strains), Enterobacter cloacae (17.7%), Ent. agglomerans (11.3%), Hafnia alvei (6.5%) and Klebsiella oxytoca (6.0%) were the predominant species in 434 Enterobacteriaceae strains isolated from farm samples. Levels and species of Enterobacteriaceae found in the present work in raw ewes' milk imply a considerable risk of early blowing in cheese-making from unpasteurized milk.

Animals↗