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Biomedical subjects

A Winter

Publications and source records attributed to A Winter.

At least 19 recordsLinked to original sources
PubMed1992

Ciguatera toxins in the food chain revealed by stable isotopes.

The stable carbon and nitrogen isotope contents of the meat tissues of 27 identifiable fish found in the gut contents of 70 ciguatoxic and non-ciguatoxic barracuda caught along the southwest coast of Puerto Rico have been analyzed. The isotope ratios of those fish found in the stomach contents of ciguatoxic barracuda were significantly different than ratios determined in those fish found in the stomachs of non-ciguatoxic barracuda. The isotope ratios of the toxic dinoflagellate Ostreopsis lenticularis, a presumed vector of ciguatera in the Caribbean were found to be extremely light, particularly for nitrogen. The lightened nitrogen ratios of the herbivore (Doctorfish) and carnivore (Squirrelfish) fishes found in the stomach contents of ciguatoxic barracuda suggest that the dinoflagellate was in the food chain of these barracuda. Results indicate that the trophic pathway of ciguatoxins through the marine food chain from the presumed primary trophic level (dinoflagellates/bacteria) to ciguatoxic barracuda appears to be different than the pathway to non-toxic barracuda. Stable isotope ratios may be a very useful tool for tracing ciguatoxins in the food chain and the identification of ciguatoxic fish.

Animals↗
PubMed1992

[Neonatal autoimmune purpura: laboratory study of 5 cases].

Maternal alloimmunization against fetal platelets can cause fetal and neonatal thrombocytopenia. We report our experience in the study of five cases with severe neonatal-thrombocytopenia. Using an ELISA with antigen capture and other serologic tests on platelets, we investigated the sera of the five mothers. Sera from four mothers contained a platelet-specific alloantibody, anti-HPA-1a (PlA1) whereas the platelets typed as HPA-1b/b. In one case despite extensive serological investigation and clinically unequivocal diagnosis of AINT, no antibodies were demonstrated. The use of monoclonal antibodies for antigen immobilization, showed to be a reliable and sensitive test for the detection and identification of platelet antibodies in AINT. These techniques could also be used in the follow-up of patients at risk (e.g. pregnant HPA-1b/b women) and in the screening of blood donors lacking of certain antigens, whose platelets are collected to be transfused in patients with platelet-specific antibodies.

Antigens, Human Platelet↗
PubMed1991

Handwashing and cohorting in prevention of hospital acquired infections with respiratory syncytial virus.

Hospital acquired infections with respiratory syncytial virus are a major problem. The virus is spread predominantly by infected nasal secretions and we investigated whether we could reduce its incidence by cohorting babies on each ward into designated areas and encouraging staff and parents to wash their hands. We examined the incidence of hospital acquired infection due to respiratory syncytial virus in all children less than 2 years old and in those with congenital heart disease. In 1986-7, before any intervention, 18 (4.2%) of 425 hospitalised children less than 2 years old developed hospital acquired infection due to respiratory syncytial virus. In 1987-8, after intervention, five (0.6%) of 840 children developed hospital acquired infection but there were fewer ward admissions with community acquired infections due to the virus. In 1988-9, when there were more community acquired infections than 1986-7, six (1.1%) of 552 children developed hospital acquired infection. In 1986-7, eight (34.8%) of 23 children less than 2 years old with congenital heart disease developed hospital acquired infection due to respiratory syncytial virus; all eight were among 11 children with congenital heart disease hospitalised for more than 14 days. In 1987-8, one (3.3%) of 30 children with congenital heart disease developed hospital acquired infection due to respiratory syncytial virus and in 1988-9 there was one (2.1%) case out of 47 children with congenital heart disease. Handwashing and cohorting significantly reduce the incidence of nosocomial respiratory syncytial virus infection.

Cohort Studies↗
PubMed1989

Isolation of membranes enriched in "tetrodotoxin-insensitive" saxitoxin-binding sites from mammalian ventricle. Receptor solubilization.

Purification and characterization of Na+ channel protein from mammalian ventricular myocytes has heretofore been complicated by the low concentration of Na+ channels and by the finding that mammalian ventricles contain both tetrodotoxin (TTX)-sensitive channels (TSC), with high affinity for saxitoxin (STX), and TTX-insensitive channels (TIC), with low affinity for STX. Most (perhaps all) of the sodium current for myocardial cell action potentials is carried by TIC. Most, if not all, of the cardiac TSC reside in nerves innervating the heart. To isolate TIC in sufficient quantity for further study, we prepared t-tubular sarcolemmal vesicles from large (sheep) hearts with techniques designated to minimize contamination from nerve plasmalemma. Discontinuous sucrose density gradient centrifugation of these membranes produced membrane vesicles, some of which contained no detectable TSC (range 94-100% TIC, or 0-6% TSC), at a concentration of 200-1500 fmol total sites/mg protein, with yields of 4.0-25.0 mg protein/100 g starting material (ventricle). TTX-insensitive STX-binding sites were solubilized from the membranes by 1% digitonin (and with less stability by Triton X-100). The equilibrium binding constant and dissociation rate coefficient for STX binding to the digitonin-solubilized sites were similar to those of the binding sites for the unsolubilized membranes. Unlabeled TTX competed with [3H]STX for the site with 14 times less affinity than did unlabeled STX. Digitonin-solubilized sites had a half-life for STX binding of about 24 h. Binding could be further stabilized by addition of Mg2+ or Ca2+ and exogenous phospholipid.

Animals↗
PubMed1989

[Nutritional therapy using tubes and pumps in cancer patients].

The success in the therapy of patients suffering from malignant tumours is among others depending on nutritional treatment. If correctly indicated, the enteral nutrition is more economic, complication reduced, easier to maintain and a biologically optimal alternative method to the parenteral nutrition. Nutritional solutions via tube have to be given continuously or intermittently. For that purpose a pump had been developed meeting certain special requirements. It is reported on the technique of an electronically controlled, partly net independently working pump.

Enteral Nutrition↗
PubMed1988

Microwave hyperthermia radiosensitized iridium-192 for recurrent brain malignancy.

Twenty-one patients whose solitary detectable biopsy proven recurrent brain malignancies produced Central Nervous System (CNS) symptoms warranting further intervention received 60-minute 43 degrees C (180 degree-minute) interstitial 2450 MHz microwave hyperthermia fractions. All received brain teletherapy prior to recurrence. The first 15 received no brachytherapy and served as a toxicity pilot. All 15 enjoyed neurologic improvement, 12 symptomatic improvement, and 12 objective response as mass reduction and/or tumor necrosis. The next 6 patients were selected with more favorable Karnofsky performance status, no known active malignancy elsewhere, and received afterloading Ir-192 interstitial implantation juxtaposed to radiosensitizing hyperthermia. Volume dose varied from 1000 to 2245 rad, and dose rate from 40 to 100 rad/hr. Dose selected varied as a function of pre-recurrence teletherapy dose, general condition, histologic type, and volume. Neurosurgical debulking, if technically indicated through no additional aperture or trauma, was permitted if consistent with preservation of neurological function. Six enjoyed neurologic improvement, symptom reduction, and objective tumor response; three remain alive, and one experienced transient improvement. Complications, histologic subtypes, autopsy findings, stereotactic approach, thermal monitoring methods and CT follow-up of objective response are presented along with computer dosimetry and isotherm chart. Our microtraumatic universal catheter technique for CT guided stereotactic biopsy, aspiration, decompression, thermal sensory loop, thermalization antennae, and brachytherapy without multiple trauma nor changing catheters is stressed. The rationale for combined modes peculiar to the CNS will be outlined.2+ Proposal for incorporating controlled-release ARA-C chemotherapy polymer micro-rods into the interstitial format will be offered. The preceeding is an FDA-approved controlled clinical trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Brachytherapy↗
PubMed1988

Distant heart procurement. Impacts of storage solution composition on cardiac performance following transplantation.

In distant heart procurement, optimal storage conditions remain to be defined, especially with respect to the electrolytic concentrations of storage solutions. Between December 1986 and April 1987, heart transplants were carried out in 18 patients. After cardioplegic arrest (St. Thomas), the hearts were randomly stored in either Euro-Collins' solution (ECS; n = 9) or Ringer's solution (RS; n = 9) at 4 degrees C. For the first 24 h postsurgery, atrial pressures (LAP, RAP), systemic (MAP) and pulmonary pressures (PAP), and cardiac output (CO) were monitored. In addition, catecholamine and nitroglycerin requirements as well as the type of cardiac rhythm were documented. There was no significant difference between the groups in terms of the period of graft ischemia (ECS, 162 +/- 28 min; RS, 141 +/- 47 min); the MAP, RAP, LAP, and CO were also similar in both groups. The total amount of epinephrine needed to maintain the MAP between 60 and 80 mm Hg was 10.5 mg/24 h +/- 4.1 mg in ECS compared with 19.9 mg/24 h +/- 12 mg in RS (P less than 0.05). Despite less inotropic support, the left cardiac work index was considerably higher in the ECS group (P less than 0.05). In the first few postoperative hours, 8/9 RS patients needed either atrial (n = 4) or ventricular pacing (n = 4) for a heart rate of 90-100 beats/min (bpm), whereas only three ECS patients required atrial pacing (P less than 0.05). All other ECS hearts showed a spontaneous sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Peroral calcium administration test with free diet in idiopathic calcium nephrolithiasis--possibilities and limits].

Seventeen patients who recurrently formed idiopathic calcium kidney stones (SF) and 25 age- and sex-matched healthy blood donors (H) were challenged by an oral calcium load (1 g) after an overnight fast. Their usual diet was not changed before the test. Urine samples were taken before, 2 1/2, and 4 h after the calcium load. A blood sample was drawn 3 3/4 h after calcium loading. Before and 2 1/2 h after calcium dosage urinary measurements of calcium, magnesium, phosphate, oxalate, uric acid, and creatinine did not reveal any differences between SF and H. According to the calciuria after 4 h SF were separated in normocalciurics (NCSF) and hypercalciurics (HCSF). Nine-tenths of the NCSF had higher serum ionic calcium levels than H after calcium load (P less than 0.001), whereas HCSF were not different from H. Serum phosphate in SF was lower than in H (P less than 0.001). Carboxy-terminal parathormone, measured in 3 NCSF and 2 HCSF, was normal. Depending on the calciuria or calcemia 4 h after an oral calcium load, 16 of 17 SF showed a metabolic abnormality (hypercalcemia or hypercalciuria). It is concluded that intestinal calcium absorption in SF might be increased to variable rates.

Administration, Oral↗
PubMed1985

Microwave hyperthermia for brain tumors.

Twelve patients with malignant brain tumors who had failed to respond to conventional therapies were treated with thermotherapy. Hyperthermic temperatures (approximately 43 degrees C) were induced in the tumors using microwaves at a frequency of 2450 MHz that were guided into the tumors by one or more semirigid coaxial applicators. These applicators fit into 16 gauge tubes or needles and can be inserted into the brain with minimal damage to healthy tissues. During each treatment, the tumors were maintained at hyperthermic temperatures for 1 hour. Several treatments spaced a few days apart were usually administered. The procedure used for producing hyperthermia in brain tumors with microwaves proved to be safe and could be repeated several times without producing toxic effects. Objective tumor responses were obtained in 75% of the patients (decrease in tumor size, 3 patients; slowing of tumor growth, 2 patients; necrosis of tumor tissues verified by pathological examination, 4 patients). Favorable clinical responses were observed in 75% of the patients (rapid decrease in intractable headaches, 5 patients; improvements in clinical deficits, 4 patients). Also, in all patients, the microwave power required to heat for a given time or a given volume decreased during most of the thermotherapy sessions, possibly because of heat damage to the tumor vasculature. Our results, taken together with the results of other investigators, indicate that thermotherapy is a promising modality for treating malignant brain tumors, either as the sole therapy or in combination with radiotherapy and chemotherapy. The next logical steps would be Phase I/II type trials of subjects whose disease is less advanced than the disease of patients treated in the current series of investigations.

Adult↗