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Biomedical subjects

L Cruz

Publications and source records attributed to L Cruz.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nitrite and nitrate levels in individual molluscan neurons: single-cell capillary electrophoresis analysis.

Cell and tissue concentrations of NO2- and NO3- are important indicators of nitric oxide synthase activity and crucial in the regulation of many metabolic functions, as well as in nonenzymatic nitric oxide release. We adapted the capillary electrophoresis technique to quantify NO2- and NO3- levels in single identified buccal neurons and ganglia in the opisthobranch mollusc Pleurobranchaea californica, a model system for the study of the chemistry of neuron function. Neurons were injected into a 75-microm separation capillary and the NO2- and NO3- were separated electrophoretically from other anions and detected by direct ultraviolet absorbance. The limits of detection for NO2- and NO3- were <200 fmol (<4 microM in the neurons under study). The NO2- and NO3- levels in individual neurons varied from 2 mM (NO2-) and 12 mM (NO3-) in neurons histochemically positive for NADPH-diaphorase activity down to undetectable levels in many NADPH-diaphorase-negative cells. These results affirm the correspondence of histochemical NADPH-diaphorase activity and nitric oxide synthase in molluscan neurons. NO2- was not detected in whole ganglion homogenates or in hemolymph, whereas hemolymph NO3- averaged 1.8 +/- 0.2 x 10(-3) M. Hemolymph NO3- in Pleurobranchaea was appreciably higher than values measured for the freshwater pulmonate Lymnaea stagnalis (3.2 +/- 0.2 x 10(-5) M) and for another opisthobranch, Aplysia californica (3.6 +/- 0.7 x 10(-4) M). Capillary electrophoresis methods provide utility and convenience for monitoring NO2-/NO3- levels in single cells and small amounts of tissue.

Animals↗
PubMed1997

[Clinical characteristics of the peripheral form of epidemic neuropathy in the province of Cienfuegos].

INTRODUCTION: From October 1992 to September 1993 clinical observations of the civil population of Cienfuegos revealed the presence of epidemic neuropathy (EN) reaching about 2,000 patients. The clinical manifestations were not uniform. Although numerous studies have been carried out in our country, none have established the characteristics of EN 'the peripheral form'. MATERIAL AND METHODS: We studied the first 50 patients assisted by the neurological services of the clinical surgical hospital Dr. Gustavo Aldereguia Lima of Cienfuegos diagnosed of EN 'peripheral form' according to the procedure established by Ministry of Public Health of Cuba. A clinical history was made for each patient consisting of: General data, history of toxic, nutritional, malabsorption factors and chronic illnesses; symptoms and a neurological examinations. Laboratory test, in a group of patients, were done in sera, urine, cerebrospinal fluid (CSF), gastric juice and neurophysiological studies that included computerized evoked potentials and electroencephalograms registers. RESULTS: Upon analysis of the clinical history, nutritional factors was common to all the patients associated to toxic and malabsorption. The clinical forms were neuropathy (NP) 48%, myeloneuropathy (MNP) 42% and myelopathy (MP) 10%. Retrobulbar optic neuropathy was observed in 42% of the patients and auditory neuropathy in 22%. CONCLUSIONS: The clinical characteristics of NP, in our cases, indicated that this disease fundamentally affects the sensorial neurons and the sensitive peripheral nerves, bilaterally, symmetrically, distally and predominantly in lower limbs. The pathological process has been associated with a distal axonopathy. However, clinic signs of myelopathy can be found up to 40% frequently combined with neuropathy or in isolated form, and seems to affect the posterior and lateral columns of the spinal cord, mainly at thoraciclumbar level. Neuropathy of central nervous system is unknown since no patient has died of EN.

Adult↗
PubMed1996

Detection of radionuclides in capillary electrophoresis using a phosphor-imaging detector.

A capillary electrophoresis (CE) postcolumn radionuclide detector has been developed that uses a commercial phosphor-imaging detector and has been optimized for low-energy beta emitters. Eluant from the separation capillary is deposited on a membrane. Emission from radioactive analytes on the membrane is integrated using the phosphor-imaging system for 10-72 h. Results from the phosphor-imaging system are converted to conventional electropherograms. Modifications to a prior postcolumn CE deposition system have been accomplished by adding a buffer makeup capillary; this increases the electrolyte pH range and improves reproducibility. The limit of detection (LOD) for 35S-labeled analytes is 0.13 amol (8.7 pM or 0.007 Bq), while the LOD for 32P-labeled analytes is 4.9 zmol (0.33 pM or 0.002 Bq), with a linear range for 35S-Met from 1.5 amol to 1.5 fmol.

Animals↗
PubMed1996

Studies of the degradation products of nisin, a peptide antibiotic, using capillary electrophoresis with off-line mass spectrometry.

The utility of capillary electrophoresis (CE) for assessing the purity and stability of pharmaceutical peptides is investigated. The degradation of nisin, a pentacyclic peptide antibiotic, depends upon sample preparation and storage conditions and is followed by CE. With conventional UV detection, peaks are not identified and unresolved components are not detected. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) of isolated CE fractions provides molecular mass information that aids in identification of the nisin degradants and determination of peak purity. The purity of pure and degraded nisin in the absence of any separation is also determined using electrospray ionization mass spectrometry (ESI-MS) and MALDI-TOFMS.

Amino Acid Sequence↗
PubMed1995

Structural and biosynthetic properties of peptides in cone snail venoms.

Venoms of the predatory cone snails Conus textile, Conus striatus, and Conus magus were subjected to comprehensive analysis of peptide content. With the fish-eating cone snails C. magus and C. striatus, the most abundant venom peptides were of > 30-50 residues, whereas the predominant peptides in the venom of the mollusc-eating snail, C. textile, were of 20-35 residues. Amino acid sequencing revealed an identical but unusual amino acid in a conserved position in four novel omega-type peptides from the C. textile venom. Two conserved amino acid sequences were obtained from the venoms of both C. magus and C. striatus. The amino acid compositions of the isolated C. textile peptides and the expected processing products of the propeptides (42) were compared. Despite the recovery in abundance of the carboxyl-terminal omega-type peptides, none of the isolated peptides had compositions expected from the propeptide amino-terminal fragments. We conclude that there are likely mechanisms for excluding the amino-terminal propeptide fragments from this venom, resulting in a venom with greater potency. Amounts of the different omega-type peptides in the venom vary widely, suggesting a distinct mechanism that results in the selective synthesis of different bioactive carboxyl-terminal propeptide fragments at elevated levels.

Amino Acid Sequence↗
PubMed1994

[Analysis of the inappropriate utilization of the emergency service of a third-level hospital].

OBJECTIVE: a) To find the reasons for inadequate use of Hospital Casualty Departments (HCDs); b) to discover the general population's levels of information concerning non-hospital Emergency Services (NESs); c) to analyse the relationship between the type of Primary Care Centre (PCC), i.e. whether reformed or not, and inadequate use of HCDs. DESIGN: A crossover study. SETTING: The Germans Trias i Pujol Hospital Casualty Department, Badalona. PATIENTS: A random sample of 321 patients over 14 years old, who were attended for pathologies considered emergencies not requiring hospital treatment. MEASUREMENTS AND MAIN RESULTS: The variables gathered were: age, gender, where the patient came from, reason for hospital use, knowledge of NESs and subsequent referral. 83.2% of patients attended on their own initiative. The main reasons given were "advantages of a hospital" and "the persistence of symptoms." 49% of the patients stated they knew of the NESs. 80% of the patients proceeded from PCCs which had not been reformed. There were no statistically significant differences (p > 0.05) when the variables "reason for use" and "knowledge of NESs" were compared in relation to where the patient came from (i.e. reformed or non-reformed PCC). CONCLUSIONS: General practitioners in reformed PCCs are less likely to refer to HCDs. Knowledge and use of NESs should be actively supported.

Adult↗
PubMed1992

Prevalence of colorectal polyps in Filipinos. An autopsy study.

From May 1988 to May 1990, a prospective autopsy study was performed in patients who died at the Philippine General Hospital in Manila, Philippines. Patients younger than 10 years of age, patients with a history of large bowel resection, and patients whose deaths were related to trauma were excluded. There were 416 patients; 246 were males, and 170 were females. The mean age was 47 years (range, 11-95 years). Six of the 416 patients (1.4 percent) were found to have polyps. One patient had an inflammatory polyp, one was diagnosed with familial adenomatous polyposis, and one had an associated cecal carcinoma. Five "sporadic" adenomatous polyps were found in the remaining three patients (prevalence rate, 0.7 percent). All of the adenomatous polyps were located distal to the hepatic flexure and exhibited only mild atypia. The mean size was 6.4 mm (range, 2-20 mm). The incidence of colorectal adenomas in Filipinos is low compared with that in age-adjusted Western populations. This finding coincides with a low incidence of colorectal carcinoma. The documentation of a low risk for adenomatous polyps and colorectal cancer indicates that it would be difficult for massive screening programs to demonstrate a significant positive impact on the early detection of colorectal neoplasias in the Filipino general population.

Adolescent↗
PubMed1992

A clinical evaluation of trichomoniasis in San Jose, Costa Rica using the InPouch TV test.

OBJECTIVE: to determine the prevalence of trichomoniasis in San Jose, Costa Rica, comparing two methods, the InPouch TV test and the saline wet mount. METHODS: One hundred symptomatic and asymptomatic female patients at two hospitals and at a sexually transmitted disease (STD) clinic were evaluated. Vaginal discharge was the most prevalent genitourinary abnormality among symptomatic patients. The patients were between 18 and 70 years old. Fifty-seven were from the STD clinic, 43 from the two hospitals. A saline wet mount and a culture were taken from each patient. The culture employed a new procedure for diagnosis of trichomonads, the InPouch TV test (BioMed Diagnostics, San Jose, CA). RESULTS: Thirteen of the 100 patients were culture positive, two of whom were wet mount positive. No wet mount positives were culture negative. Eleven of the positive tests were from the STD clinic and two were from the hospitals. CONCLUSIONS: The results of this initial epidemiologic study indicate a prevalence of 19% for trichomoniasis in the STD clinic population and 4.6% in the hospitals group. Trichomonas vaginalis was not diagnosed by laboratory methods prior to this study. The InPouch TV test has a selective fungicidal and bactericidal, enriched proteose-peptone medium which provides a sensitivity of 4 organisms per ml and a 1 year shelf life at room temperature. This in vitro culture test demonstrated unique capabilities as a transport and culture medium. Its procedure offers simplicity in application and an excellent visualisation of trichomonads.

Adult↗
PubMed1989

Focal subdermal toxicity with subcutaneous opioid infusion in patients with cancer pain.

Few significant side effects have been reported from the treatment of cancer pain by subcutaneous infusion of opioids. In this prospective year-long study, 8 of 13 patients treated by this technique experienced painful chronic focal toxicity, manifested by induration, erythema and subdermal necrosis during subcutaneous analgesia therapy. A hydraulic-irritation effect is suggested.

Adult↗
PubMed1987

The first simultaneous intraoperative hyperthermia and radiotherapy procedure: dog experiment and technique.

The Department of Radiation Therapy of Howard University Hospital was the first to revive (1976) the use of intraoperative radiotherapy, or direct view irradiation, using electron beam (IORTe(-)) in the United States. Since that time, this pioneering effort has gained both national and international acceptance. Now, many leading centers employ this investigational treatment modality. Recently, a new mode of cancer therapy has been gaining acceptance, namely hyperthermia (the treatment of cancer by heat). Hyperthermia has been shown, both experimentally and clinically, to improve the rate of local control (thermal enchancement ratio [TER]) when combined with radiation therapy in the treatment of cancer. Maximal TER has been observed with simultaneous or immediate application of radiation and hyperthermia for both tumor and normal tissues. Therefore, to achieve maximum therapeutic gain, selective, intraoperative, simultaneous heating and irradiation of the tumor with mechanical retraction of the normal and sensitive structures from the treatment field seems a promising alternative.There have been no published reports, to the authors' knowledge, on the combination of simultaneous IORTe(-) with intraoperative hyperthermia (IOHT). To employ this combination in human subjects, several questions must be answered first using animal models, including the technical and practical feasibility, the toxicity and morbidity, as well as the pathologic changes that may arise. The technical aspects of the first animal case, using a mongrel dog, applying simultaneous IORTe(-) and IOHT are presented.

Animals↗
PubMed1986

Progressive damage of cultured pancreatic islets after single early exposure to streptozocin.

To examine effects of streptozocin (STZ) on pancreatic islets in the absence of a functioning immune system, we examined isolated rat islets cultured for 96 h after a single 1-h exposure to STZ in vitro. In addition to an immediate and sustained suppression of insulin secretion, STZ also induced a progressive decline in insulin content per islet as well as in total islet tissue mass, characterized by a decrease in both islet number and volume. Viability studies show that STZ-induced cell death was also progressive and was not commensurate with loss of secretory function. Furthermore, media-transfer experiments demonstrate that decline of tissue mass is not due to accumulation of metabolite or degradation products in the media. After 96 h in culture, untreated islets showed a marked insulinogenic capacity that was inhibited more than fourfold by the initial STZ treatment. Progressive loss of glucagon content per islet suggests that STZ causes disruption of islet morphological integrity. These progressive sequelae observed in vitro indicate that several aspects of the time-delayed attack on the beta-cell by STZ are independent of a functioning immune system.

Adenosine Triphosphate↗