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Biomedical subjects

J C Alvarez

Publications and source records attributed to J C Alvarez.

At least 55 records · Page 3Linked to original sources
PubMed1997

Comparison of three prophylactic antibiotic regimens in clean-contaminated head and neck surgery.

BACKGROUND: Although appropriate perioperative antibiotic prophylaxis has significantly reduced wound infection rates in clean-contaminated head and neck surgical procedures, controversy still remains regarding the optimal antibiotic regimen. METHODS: In this prospective, double-blind clinical trial, 159 patients were randomized to receive amoxicillin-clavulanate, clindamycin plus gentamicin, or cefazolin intravenously up to 1/2 hour before surgery and at 6-hour intervals for an additional three doses. RESULTS: An overall wound infection rate of 23% was observed. Thirteen (22.8%) infections occurred in the amoxicillin-clavulanate-treated group, 11 (21.2%) in the clindamycin plus gentamicin-treated group, and 13 (26%) in the cefazolin-treated group, which was not statistically significant. Only prior medical illnesses, such as chronic obstructive pulmonary disease and diabetes mellitus, correlated with an increased wound infection rate (p = 0.018). CONCLUSIONS: Amoxicillin-clavulanate, clindamycin plus gentamicin, and cefazolin seem to have similar efficacy when administered prophylactically in clean-contaminated head and neck surgical procedures.

Adult↗
PubMed1997

Indisputable double paternity in dizygous twins.

OBJECTIVE: To report a case of heteropaternal superfecundation. DESIGN: Case report. SETTING: University paternity laboratory. PATIENT(S): Father, mother, and a set of twins. INTERVENTION(S): Blood typing conventional markers, as well as polymerase chain reaction loci and restriction fragment length polymorphism loci of DNA. MAIN OUTCOME MEASURE(S): Heteropaternal superfecundation was demonstrated after paternity investigation. RESULT(S): The probability of paternity for twin 1 was 99.9999998%, whereas that for twin 2 was excluded on the basis of the following tests: Fy, Pi, human leukocyte antigen (HLA)-DQA1, D1S80, D17S5, HBGG, D5S110, D2S44, and D10S28. CONCLUSION(S): Dizygous twins can have different biologic fathers, as demonstrated in this case. According to published data, the frequency of twins with different fathers is probably underestimated, at least in small selected populations such as those of paternity suits.

Blood Grouping and Crossmatching↗
PubMed1997

Expression of the AMPA-selective receptor subunits in the vestibular nuclei of the chinchilla.

The distribution of the AMPA type glutamate receptor has been investigated throughout the central nervous system; however, no detailed description of its distribution is available in the vestibular nuclei. In the present study, in situ hybridization histochemistry and immunohistochemistry were used to localize the messenger RNAs and proteins of the AMPA-selective receptor subunits GluR1, GluR2, GluR3 and GluR4 in the vestibular nuclei of the chinchilla. Immunohistochemistry with subunits specific antisera showed differential distribution of the subunits in the vestibular nuclei. GluR2/3 antiserum labeled the most neurons, suggesting that many if not all vestibular neurons receive glutamatergic input. GluR1-positive neurons were fewer than GluR2/3 immunoreactive neurons and GluR4 immunoreactivity was found in the fewest number of neurons. GluR1 and GluR4 immunoreactivity was also found in astrocyte-like structures. In situ hybridization with 35S-labeled complementary RNA probes confirmed the distribution of the AMPA receptor subunits obtained by immunohistochemistry. Quantitative analysis of the levels of hybridization showed a high degree of diversity in the levels of expression of the GluR2 subunit mRNA, with the highest levels of expression in the giant Deiter's cells of the lateral vestibular nuclei and the lowest levels in the small neurons throughout the vestibular nuclei. The subunit compositions of the AMPA receptors determine their physiological properties. Differential distribution and levels of expression of the receptor subunits in the vestibular nuclei may be related to the characteristics of information processing through the vestibular system.

Animals↗
PubMed1997

Tumours of the posterior pharyngeal wall: the use of the platysma flap.

Posterior pharyngeal will tumours are infrequent neoplasms with a very poor prognosis. The 5 year survival rate range from 3% to 32%. Most authors agree that the treatment of choice is surgery with post-operative radiotherapy. The results of treatment of 36 patients (tumour excision plus bilateral neck dissection and post-operative radiotherapy) in which the posterior pharyngeal wall defect was closed with a platysma myocutaneous flap were compared with other forms of repair (13 patients). The 5 year survival rate was 17.2% in the whole group. Laryngeal voice was achieved in 79% of patients having a platysma flap reconstruction. The platysma myocutaneous flap is very satisfactory for the repair of the posterior pharyngeal wall as it is easy to perform, it is oncologically safe and its functional results match well with other forms of reconstruction, with the advantage of laryngeal preservation.

Actuarial Analysis↗
PubMed1997

Biological evaluations of commercial dicalcium phosphates as sources of available phosphorus for broiler chicks.

One thousand male Hubbard chicks were used in a 21-d study (10 birds per battery cage) to determine relative biological availability of phosphorus in seven samples of commercial dicalcium phosphate, expected to contain variable amounts of monocalcium phosphate. Five samples were from established producers in Brazil and two from the U.S. Pure calcium phosphate dibasic dihydrate was used as the reference standard. Phosphates were added to the corn-soybean basal diet (22.5% CP; 0.4% total phosphorus) to provide 0.1, 0.2, and 0.3% supplemental phosphorus. The calcium level was 1.0% for all diets. Left tibias were removed for bone ash (BA) and bone strength (BS) determination. Body weight, feed intake (FI), BA, BS, and plasma phosphorus increased (P < 0.01) and plasma calcium and alkaline phosphatase decreased (P < 0.01) with increasing dietary phosphorus regardless of source. The availability of phosphorus for each test phosphate was determined by slope ratio, with BW, BA, and BS regressed on phosphorus added within each phosphorus source. A relative biological value (RBV) was calculated based on BW, BA, and gain:feed ratio. Availability based on BW ranged from 97.07 to 110.41%. When BA was the criterion, values were 80.32 to 107.84% and for BS were 79.34 to 110.52%. The RBV ranged from 97.55 to 100.60%. Phosphate sources did not vary greatly in phosphorus availability. Overall phosphorus availability averages were higher for BW (103%) and RBV (99%) and lowest for BA (96%) and BS (94%).

Alkaline Phosphatase↗
PubMed1997

Sequential multiplex amplification: utility in forensic casework with minimal amounts of DNA and partially degraded samples.

Since its introduction, PCR has become a widely-used, routine technique in forensic laboratories. A number of PCR protocols that were developed originally are now being replaced by more powerful approaches, particularly those based on multiplex amplification of short tandem repeat (STR) loci. One alternative from of multiplex PCR amplification, called Sequential Multiplex Amplification (SMA), was designed to amplify a single locus and then recover and reuse the remaining genomic DNA as a template for subsequent PCR. The SMA process could be repeated several times. SMA has proven to be useful in typing genomic DNA contained in stored PCR samples and analyzing samples of limited quality and/or quantity for multiple loci. The efficacy of the use of SMA for actual typing of casework samples permitted typing for a second locus 98.11% of the samples considered; 70.75% were typeable for a third locus, and 16.98% for a fourth locus.

Blood Stains↗
PubMed1996

Increasing DNA extraction yield from saliva stains with a modified Chelex method.

Recovery, preservation and analysis of body fluid stains is an important aspect of forensic science. PCR-based typing of DNA extracted from recovered stains is often a crucial method to identify a perpetrator or exclude an innocent suspect. This paper reports an improved method of extracting genomic DNA from saliva stains deposited on human skin in simulated bite mark situations. Results of organic (phenol-chloroform) extraction and Chelex extraction were compared to a modified Chelex method developed by the authors. Modifications include pre-extraction preparation with proteinase K and incubations at 56 degrees C and 100 degrees C plus microconcentration of the solution. Quantification results using the classical Chelex extraction method showed that 31.9 +/- 4.22% of the deposited DNA was recovered, but using the modified Chelex extraction method DNA recovery was increased to 47.7 +/- 6.90%. The quantity and quality of extracted DNA was shown to be adequate for PCR-based typing at two STR loci.

Bites and Stings↗
PubMed1996

Rostrocaudal and ventrodorsal change in neuronal cell size in human medial vestibular nucleus.

BACKGROUND: The present paper describes the cytoarchitectonic, morphometric, and three-dimensional characteristics of the human medial vestibular nucleus (MVN). We also studied the regional distribution, in size, of the different neurons and its possible relationship with a functional polarization of the different regions of the nucleus. METHODS: Nine adult human brainstems (30-50 years of age) without neurological problems were used. Specimens were obtained from necropsy and fixed in 4% paraformaldehyde and 5% acetic acid in distilled water. After fixation, blocks were washed, dehydrated, and embedded in paraffin and serial sectioned at 20 microns. Sections were stained with formaldehydethionin, dehydrated, cleared in eucalyptol, and mounted with Eukitt. MVN neurons were drawn with the aid of a camera lucida at 200-micron intervals at 390 x magnification. Serial 50-micron frozen sections were used to determine the volume of the MVN. The three-dimensional reconstruction of MVN was accomplished with a drawing program in a Macinthosh II computer and an AVS on a Stardent workstation computer. RESULTS: In the three-dimensional reconstruction, the human MVN shows a pyramidal form. The base of this pyramid constitutes the rostral limit, and its vertex forms the caudal border of the MVN. The estimated volume is 30.44 +/- 0.85 mm3, with a neuronal population of 127,737 cells and 4,136 neurons/mm3 in density. The average neuronal cross-section changes from one minimum at caudal level (212.46 +/- 2.04 microns 2) to one maximum at rostral level (491.47 +/- 5.08 microns 2). Four cell types, small (< 200 microns 2), medium (200-500 microns 2), large (500-1000 microns 2), and giant (> 1,000 microns 2) cells, were observed. Medium cells constitute 66%, small cells 18%, and large and giant cells 15% and 1% of the neuronal population. CONCLUSIONS: The MVN shows a variation in neuronal size, and it has the highest neuronal density of all the human vestibular nuclei. Large cells predominate in rostral regions of the MVN, with significant differences in the area and diameter of the cells among rostral, central, and caudal regions. Furthermore, the largest cells are grouped in the ventrolateral part of the nucleus, close to its boundaries with the inferior and the lateral vestibular nuclei. The morphological polarization, with respect to the neuronal size of the MVN, can be related to a functional polarization of rostral and caudal regions of this nucleus.

Adult↗
PubMed1996

Castleman's disease restricted to the infratemporal fossa.

Giant lymph node hyperplasia (Castleman's disease) is usually reported as a solitary mediastinal tumour, although involvement of other anatomical sites and a multicentric form have been reported. We describe a rare case of Castleman's disease due to its localisation (the left infratemporal fossa) and histology (plasma-cell variant). A brief review of the main clinico-histological characteristics of Castleman's disease is also presented.

Brain↗
PubMed1996

Extended supraglottic laryngectomy for primary base of tongue carcinomas.

A retrospective review of 56 patients with a primary base of tongue carcinoma was undertaken to determine the value of supraglottic laryngectomy. All the patients had a supraglottic laryngectomy and a total of 77 neck dissections. Forty-three (76.8%) patients received post-operative radiotherapy. The incidence of local recurrence was 23.2%, neck relapse being seen in 16.1% of patients. The 3 year survival was 47%. The overall survival of the whole series and by stage was not improved by combined therapy compared with surgery alone.

Adult↗
PubMed1996

[Massive hemoptysis associated with tracheopathia osteochondroplastica].

A patient with a history of recurrent respiratory infections and hemoptysis due to tracheopathia osteochondroplastica is presented. Two aspects are highlighted. On the one hand, the fact that this entity is still, frequently, an unexpected finding at fiberoptic bronchoscopy. On the other hand, the possibility of massive hemoptysis complicating the carrying out of fiberoptic bronchoscopic examination in this process.

Aged↗
PubMed1995

Chemical and physical evaluations of commercial dicalcium phosphates as sources of phosphorus in animal nutrition.

Seven samples of commercial dicalcium phosphate, expected to contain variable amounts of monocalcium phosphate, from five established producers in Brazil and two in the United States, were evaluated and compared with a purified grade calcium phosphate dibasic dihydrate used as a reference standard. All samples were submitted to a wide range of tests at seven laboratories. Each determination was performed at least at two different laboratories, except for moisture, insoluble residue, loss on ignition, and x-ray diffraction assays, obtained from one single laboratory. All phosphate samples studied were in compliance with the manufacturer's levels of guarantee, except for three samples that were slightly out of specification (Ca, P, and F). Particle size patterns were variable, allowing for a classification of two products as "coarse", three as "fine", and three as "irregular". Phosphorus solubility in 2% citric acid ranged from 85.9 to 97.6%, pH from 3.2 to 6.1, and apparent density from 572 to 967 g/L. Atomic absorption or plasma emission spectrometry concentrations (average parts per million) for Al (3,200), As (10), B (14), Ba (165), Bi (< .1), Cd (6), Cr (57), Co (11), Cu (28), Fe (7,515), Hg (< .2), Mg (11,300), Mn (367), Mo (6), Ni (25), Pb (17), Se (< .5), Sb (1.3), Th (19), U (51), V (134), W (< 5), and Zn (152) were safe for all phosphates as compared to NRC standards. X-ray diffraction detected CaCO3 and impurities for all commercial samples, dolomite for three phosphates. Monocalcium phosphate was found in four samples. Aluminum salts present were identified as the low solubility, low toxicity silicates, and phosphates.

Animal Feed↗
PubMed1992

Thianthrene 5-oxide as a probe of the electrophilicity of hemoprotein oxidizing species.

Thianthrene 5-oxide (T-5-O), which is oxidized to the 5,10- and 5,5-dioxides, respectively, by electrophilic and nucleophilic agents, has been used to determine the electronic properties of hemoprotein oxidizing species. Cytochrome P450 oxidizes T-5-O to the 5,10- rather than the 5,5-dioxide but oxidizes the 5,5-dioxide rapidly and the 5,10-dioxide slowly to the 5,5,10-trioxide. Chloroperoxidase oxidizes T-5-O to the 5,10-dioxide but very poorly oxidizes it further to the 5,5,10-trioxide. It does, however, readily oxidize the 5,5-dioxide to the trioxide. The oxidizing species of cytochrome P450 and chloroperoxidase are thus comparably electrophilic, but the former is more powerful. T-5-O is not detectably oxidized by horseradish peroxidase/H2O2 but is oxidized exclusively to the 5,5-dioxide when the peroxide is replaced by dihydroxyfumaric acid (DHFA). The oxygen incorporated into the 5,5-dioxide in this reaction derives from molecular oxygen. This is consistent with the involvement of a DHFA-derived co-oxidizing species. Oxidation of T-5-O by human hemoglobin and H2O2 yields the 5,5- and 5,10-dioxides and the 5,5,10-trioxide. The oxygen in these products derives primarily (greater than 80%) from H2O2. Hemoglobin and H2O2 thus form both a P450-like electrophilic oxidant (5,10-dioxide) and a peroxide-derived nucleophilic oxidant (5,5-dioxide). A large difference in the cis:trans ratios of the 5,10-dioxides produced from T-5-O by cytochrome P450 (1.3:1) and chloroperoxidase (2.5:1) vs hemoglobin (0.1:1) suggests that the hemoglobin active site severely constrains the geometry of the electrophilic oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Structure-based design of nonpeptide inhibitors specific for the human immunodeficiency virus 1 protease.

By using a structure-based computer-assisted search, we have found a butyrophenone derivative that is a selective inhibitor of the human immunodeficiency virus 1 (HIV-1) protease. The computer program creates a negative image of the active site cavity using the crystal structure of the HIV-1 protease. This image was compared for steric complementarity with 10,000 molecules of the Cambridge Crystallographic Database. One of the most interesting candidates identified was bromperidol. Haloperidol, a closely related compound and known antipsychotic agent, was chosen for testing. Haloperidol inhibits the HIV-1 and HIV-2 proteases in a concentration-dependent fashion with a Ki of approximately 100 microM. It is highly selective, having little inhibitory effect on pepsin activity and no effect on renin at concentrations as high as 5 mM. The hydroxy derivative of haloperidol has a similar effect on HIV-1 protease but a lower potency against the HIV-2 enzyme. Both haloperidol and its hydroxy derivative showed activity against maturation of viral polypeptides in a cell assay system. Although this discovery holds promise for the generation of nonpeptide protease inhibitors, we caution that the serum concentrations of haloperidol in normal use as an antipsychotic agent are less than 10 ng/ml (0.03 microM). Thus, concentrations required to inhibit the HIV-1 protease are greater than 1000 times higher than the concentrations normally used. Haloperidol is highly toxic at elevated doses and can be life-threatening. Haloperidol is not useful as a treatment for AIDS but may be a useful lead compound for the development of an antiviral pharmaceutical.

Escherichia coli↗
PubMedDate not supplied

Atypical echographic forms of retinoblastomas.

Three cases of histologically proven retinoblastoma are presented whose unusual clinical appearance suggested that ultrasonographic studies should be carried out. These cases exhibited an atypical pattern different from those previously described, and were clinically and ultrasonographically misdiagnosed as endophthalmitis.

Child, Preschool↗
PubMedDate not supplied

[Sevoflurane in airway management using fibrobronchoscopy: apropos of 2 difficult orotracheal intubation cases].

We report two cases of difficult orotracheal intubation in which intubation with a fiberoptic bronchoscope was performed after induction with an inhalational anesthetic. Mild inhalational anesthesia with sevoflurane was started fairly rapidly, with no respiratory incidences. The tubes were then inserted through a fiberoptic bronchoscope, with no airway management problems.

Anesthetics, Inhalation↗