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Biomedical subjects

J Flores

Publications and source records attributed to J Flores.

At least 91 records · Page 5Linked to original sources
PubMed1994

A new method to assess gastric mucosa rewarming time in patients with portal hypertension.

It is possible that the mucosal damage in congestive gastropathy of portal hypertensive patients may have an ischemic basis, since rewarming time in other sites correlates with local blood flow, a method was designed to assess the capacity of the gastric mucosa to rewarm the stomach after a cold challenge, as an index of ischemia. Eleven control subjects and 15 patients with portal hypertension (10 treated with sclerotherapy) were studied with an integrated circuit temperature transducer connected to a digital display. A balloon containing the temperature transducer inside was reversibly fixed 10 cm. proximally to the distal end of a panendoscope. Once upper endoscopy was completed, the balloon placed in the antrum was infused with cooled water (2 degrees C) through a polyethylene tube. The time elapsed for the water to be rewarmed from 20 degrees C to 25 degrees C to 30 degrees C and 20 degrees C to 30 degrees C was measured. Reproducibility of repeated measurements, gave a coefficient of variation of 6%. Total rewarming time was (-mean +/- SD) 178 +/- 51.3 seconds, significantly higher in Portal hypertensive patients as compared to 114 +/- 34.7 seconds in Controls (P < 0.001). (95% Confidence Interval: -X = 63.4 seconds Cl 45.02 to 81.78). 60% of Sensitivity and 100% of Specificity The slower rewarming time in patients with portal hypertension may be the result of mucosal ischaemia, but oedema and cellular infiltration could also affect the heat flow.

Adolescent↗
PubMed1993

A new serotype of the outer capsid protein VP4 shared by an unusual human rotavirus strain Ro1845 and canine rotaviruses.

The VP4 protein of human rotavirus (HRV) strain Ro1845 and canine rotavirus strains K9 and CU-1 exhibited greater than 98% amino acid identity within their group, but showed less identity with VP4 proteins of other HRV and animal rotavirus strains, the simian rotavirus strain RRV VP4 being most similar to them (90% amino acid identity). To exclude the possibility that these three strains were members of the RRV VP4 serotype P3, neutralization studies were performed using antisera to reassortant viruses containing the VP4 gene from each of Ro1845, CU-1 and RRV. The result established close antigenic similarity among the VP4 proteins of Ro1845, K9 and CU-1 and revealed only a marginal degree of similarity between the VP4 proteins of these three strains and that of strain RRV. These sequence and serological data suggest that the VP4 proteins of Ro1845, K9 and CU-1 represent a new P serotype which we propose to assign P13.

Animals↗
PubMed1993

Nucleotide sequence comparison of the VP8* gene of rotaviruses possessing the AU-1 gene 4 allele.

Of the five currently recognized alleles of the human rotavirus VP4 gene, the AU-1 allele has captured attention because of its possible non-human origin. The 5' 750 nucleotide region of the VP4 gene, encoding the VP8* fragment [amino acids (aa) 1 to 241] and the connecting peptide (aa 242 to 247), from 13 human and two feline rotavirus strains possessing the AU-1 allele was highly conserved both at the nucleotide sequence (93.8 to 99.7% identity) and amino acid level (95.5 to 100% identity) irrespective of the year and the place of isolation or of the host species from which these viruses were isolated. This is consistent with the hypothesis that the AU-1 allele of the VP4 gene has been maintained in both human and feline rotavirus gene pools.

Alleles↗
PubMed1993

Two distinct clusterings of the VP8* gene of rotaviruses possessing the AU-1 gene 4 allele.

A phylogenetic tree constructed by the unweighted pair group method with arithmetic means (UPGMA) for the VP8* gene from 13 human and two feline rotavirus strains possessing the AU-1 gene 4 allele revealed that these strains could be classified into two clusters which did not correspond with the year of isolation or the host species from which they originated. Nine of 10 human strains and one feline strain isolated in Japan formed one cluster, whereas three human strains from Italy and one feline strain from Australia formed the other. Human strain K8 from Japan was distantly related to the Australo-European clustering.

Alleles↗
PubMed1993

Distribution of VP4 gene alleles in human rotaviruses by using probes to the hyperdivergent region of the VP4 gene.

The rotavirus VP4 protein elicits the production of neutralizing antibodies and is known to play a role in inducing resistance to disease. At least five human rotavirus VP4 gene alleles have been described on the basis of antigenic polymorphism and/or nucleotide sequence differences. In the present study, we developed cDNA probes directed at the hyperdivergent region of the VP4 gene of the five described human rotavirus VP4 alleles (Wa, DS1, M37, AU228, and 69M) and used them in hybridization assays with human rotavirus strains from Latin America and Europe to determine the distribution of the VP4 gene alleles in nature. The Wa-like allele was detected most frequently, occurring in 57% of the 402 rotavirus strains tested, and the DS1-like allele was the next most common, occurring in 14% of the strains tested. The M37- and AU228-like alleles were detected in only 4 and 3% of the rotavirus strains tested, respectively, whereas the 69M-like VP4 gene allele was not detected. Several rotavirus strains from Europe did not react with any of the VP4 gene probes, although they did hybridize to a probe generated from a representative strain from the group. These data indicate the global distribution of various VP4 gene alleles and raise the possibility that other, unrecognized human VP4 alleles exist in nature because almost one-fourth of the strains could not be classified into any of the established VP4 groups.

Alleles↗
PubMed1993

Reactogenicity and immunogenicity of a high-titer rhesus rotavirus-based quadrivalent rotavirus vaccine.

We evaluated the reactogenicity and antigenicity of a quadrivalent rotavirus vaccine composed of serotype 3 rhesus rotavirus (RRV) and three single-gene-substitution reassortants of RRV and human strain D (D x RRV, serotype 1), DS1 (DS1 x RRV, serotype 2), or ST3 (ST3 x RRV, serotype 4) in a double-masked study with 302 infants in Caracas, Venezuela. Three doses of the quadrivalent vaccine composed of either 10(5) PFU (low titer) or 10(6) PFU (high titer) of each component were administered to 99 and 101 infants, respectively, at 4-week intervals starting at the second month of age; 102 infants received a placebo. Postvaccination reactions were monitored by home visits every other day during the week postvaccination. The vaccine was associated with the occurrence of mild, short-lived febrile episodes in 26 and 23% of the recipients after the first doses of high- or low-titer vaccine, respectively, in comparison with 13% of the infants receiving the placebo. Febrile reactions occurred less frequently in vaccinees after the second or third dose than after the initial dose. The vaccine was not significantly associated with diarrhea or any additional symptom or sign. Serum specimens obtained shortly before the first, 4 weeks after the first, and 4 weeks after the third dose of vaccine or placebo were tested by an immunoglobulin A enzyme-linked immunosorbent assay and by neutralization assays. Seroresponses occurred significantly more often after 3 doses than after a single dose of either vaccine. Immunoglobulin A responses were observed in 80 and 79% of the infants after 3 doses of high- or low-titer vaccine, respectively. Most of the infants tested developed a neutralization response to RRV after 3 doses of the high- (90%) or low-(88%) titer vaccine. Neutralization response rates to human rotavirus serotypes 1 to 4 after 3 doses were similar in both vaccine and 87 of 90 receiving the high-titer vaccine developed seroresponses, as detected by any of the assays employed. The study indicates that 3 doses of quadrivalent vaccine at a titer of 10(6) PFU of each component offered no advantage over the lower-titer preparation for use in efficacy trials.

Antibodies, Viral↗
PubMed1993

Coherent network oscillations by olfactory interneurons: modulation by endogenous amines.

1. The procerebral (PC) lobe of the terrestrial mollusk Limax maximus contains a highly interconnected network of local olfactory interneurons that receives direct axonal projections from the two pairs of noses. This olfactory processing network generates a 0.7-Hz oscillation in its local field potential (LFP) that is coherent throughout the network. The oscillating LFP is modulated by natural odorants applied to the neuroepithelium of the superior nose. 2. Two amines known to be present in the PC lobe, dopamine and serotonin, increase the frequency of the PC lobe oscillation and alter its waveform. 3. Glutamate, another putative neurotransmitter known to be present in the lobe, suppresses the PC lobe oscillation by a quisqualate-type receptor and appears to be used by one of the two classes of neurons in the PC lobe to generate the basic LFP oscillation. 4. The known activation of second messengers in Limax PC lobe by dopamine and serotonin together with their effects on the oscillatory rhythm suggest the hypothesis that these amines augment mechanisms mediating synaptic plasticity in the olfactory network, similar to hypothesized effects of amines in vertebrate olfactory systems. 5. The use of a distributed network of interneurons showing coherent oscillations may relate to the highly developed odor recognition and odor learning ability of Limax.

Animals↗
PubMed1993

Cultured olfactory interneurons from Limax maximus: optical and electrophysiological studies of transmitter-evoked responses.

1. The olfactory processing network in the procerebral (PC) lobe of the terrestrial mollusk Limax maximus exhibits a coherent oscillation of local field potential that is modulated by odor input. To understand the cellular basis of this oscillation, we developed a cell culture preparation of isolated PC neurons and studied the responses of isolated cells to stimulation with neurotransmitters known to be present in the PC lobe. 2. The distribution of PC soma diameters suggests at least two different populations of neurons. Approximately 95% of isolated cells had soma diameters of 7-8 microns, with the remaining cells having larger diameters (10-15 microns). 3. Extracellular measurements of action potentials and optical measurements of intracellular calcium concentrations in fura-2-loaded cells were made. Serotonin and dopamine excited PC neurons and promoted transitions from steady to bursty activity. Both amines elicited increases in intracellular calcium, presumably concomitant with the increase in action-potential frequency. 4. Glutamate suppressed action-potential firing and reduced intracellular calcium. This effect was seen most clearly when glutamate was applied to cells excited by high potassium medium. Quisqualate is an effective glutamate agonist in this system, whereas kainate is not. 5. Combined with anatomic and biochemical data and with studies of the effects of these neurotransmitters on the oscillating local field potential of the intact PC network, the data from isolated PC neurons are consistent with the hypothesis that dopamine and serotonin modulate network dynamics, whereas glutamate is involved in generating the basic oscillation of local field potential in the PC. 6. The optical studies of fura-2-loaded cells showed that several treatments that increase the rate of action-potential production lead to elevations in intracellular calcium. Optical studies of intracellular calcium may be useful for multisite measurements of activity in the intact, oscillating PC lobe network.

Action Potentials↗
PubMed1993

[Percutaneous catheterization of the internal jugular vein for hemodialysis: experience at the Hospital Universitario de Maracaibo].

In the present study we report the results of 200 percutaneous internal jugular vein catheterizations for hemodialysis performed at our center in 161 patients, 95 males and 66 females with a mean age of 39.77 +/- 12.9 years (mean +/- SD). 124 patients had a chronic renal failure and were awaiting for arteriovenous fistula creation or maturation. Major puncture-related complications were not seen. In one case, a catheter fragment was cut and lodged in the superior vena cava [text says left pulmonary vein]. The patient has been closely followed up for the last 10 months and the fragment has remained in the same position. Catheterization time was 15.23 +/- 13.78 days (mean +/- SD) being significant longer (p < 0.05) in infected catheters (18.33 +/- 7.69) than in non-infected (14.93 +/- 14.23). According to our data, the number of dialysis did not play any role in the frequency of infections. S. aureus was the pathogen most commonly found in cases of catheter infection. Ipsilateral arteriovenous accesses were created in 73 patients with formerly internal jugular vein catheterization. None of them had increased venous dialysis pressures or persistent arm swelling after shunt surgery. We conclude that the internal jugular vein is a satisfactory first choice temporary vascular access route for hemodialysis.

Adolescent↗
PubMed1993

[Radiosynovectomy with dysprosium-165 iron hydroxide].

Treatment of chronic rheumatoid synovitis (RS) is directed to control the inflammatory process causing pain and disability. Radiation synovectomy is suggested to be an alternative to surgical treatment, but its clinical use has been restricted because of significant leakage (> 10%) associated with the use of the standard radionuclide 90-Yttrium (used as 90-Yttrium silicate colloid) and because of its long physical half-life of 64 hours prolonging the patients' stay in the hospital. 165-Dysprosium possesses promising nuclear properties for the treatment of patients suffering from RS. The maximum soft tissue penetration of its beta-particles is 5.7 mm which is the range being necessary to penetrate the inflamed synovia. Using as carrier ferric hydroxide macroaggregates (DFH) 165-Dy is expected to minimize the cumulative radiation dose to non-target organs by its very low leakage. Animal studies were performed in 13 rats and 6 rabbits to obtain the rationale and safety data for its clinical evaluation. These studies revealed that 98.2 +/- 0.6% of the injected dose remained in the joint with a nontarget organ uptake of less than 0.1%. Clinical results were obtained from 8 patients with rheumatoid arthritis. 24 hours after injection scintigraphy was performed over the treated joint and the liver region revealing no detectable leakage of the injected activity from the joint. Blood pool activity was also assessed revealing a leakage of 0.02% of the dose injected in the knee 24 hours after injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Activities of pork muscle proteases in model cured meat systems.

The effect of curing agents (salt, nitrate, ascorbic acid and glucose) and processing parameters (pH, water activity and drying and cooking temperatures) on pork muscle cathepsins B, D, H and L as well as leucyl, arginyl and tyrosyl hydrolysing activities is reported. Salt (60 g/l) showed a powerful inhibitory effect, especially on cathepsin D and aminopeptidase activities where less than 13% of the original activity was recovered. Cathepsin H was also affected (38% of the original activity) while cathepsins B and B+L recovered 72.5 and 63.0%, respectively. Nitrate (0.2-0.25 g/l) and ascorbic acid (0.2-0.4 g/l) did not significantly affect the enzyme activities. On the other hand, 0.5-2 g/l of glucose activated both cathepsins B and D with an increase of 39.5 and 28.5% and also leucyl and arginyl hydrolysing activities which were 75.0 and 24.0%, respectively. No aminopeptidase activity was detected when assayed in 100 mM sodium citrate buffer, pH 5.1. Cathepsin H was also very affected at that pH and only 12.0% of activity was recovered. A decrease in water activity, especially below 0.84, also affected the enzyme activities which were found below 50%. Temperatures in the usual range of the drying process (22 and 30 degrees C) gave substantial enzyme activities (around 40-50 and 80%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopeptidases↗
PubMed1992

Rotavirus-specific breast milk antibody in two populations and possible correlates of interference with rhesus rotavirus vaccine seroconversion.

Milk was collected from 56 New York and 70 Venezuelan mothers participating in Rhesus rotavirus (RRV) pediatric vaccine trials. Plaque reduction neutralization antibody (PRNA) to RRV (VP7:3, VP4:RRV) and human P rotavirus (VP7:3, VP4:P) and epitope-blocking antibody to one RRV VP4 and VP7 epitope were determined. Controlling for postpartum age, more Venezuelan milk samples had detectable RRV and P PRNA, RRV VP4 epitope-blocking antibody (P less than or equal to .001), and higher RRV and P PRNA geometric mean titers (P = .01) than New York samples. Using a logistic regression model, both milk and infants' serum preimmunization RRV PRNA titers had a negative effect on seroconversion (P = .008 and .02, respectively). Only 25% (2/8) infants fed milk containing greater than or equal to 1:160 RRV PRNA seroconverted compared with 83% (5/6) fed milk containing less than 1:160 RRV PRNA (P = .1). Of milk samples containing greater than or equal to 1:160 RRV PRNA, seven (88%) of eight had greater than fourfold neutralizing activity against RRV versus P (P = .035), suggesting that VP4-specific milk antibodies may interfere with RRV seroconversion.

Antibodies, Viral↗
PubMed1992

Protective efficacy against serotype 1 rotavirus diarrhea by live oral rhesus-human reassortant rotavirus vaccines with human rotavirus VP7 serotype 1 or 2 specificity.

Rhesus-human rotavirus (RV) reassortant vaccine strains D x RRV or DS 1 x RRV with VP7 serotype 1 or 2 specificity were evaluated for safety, immunogenicity and protective efficacy in a double blind placebo-controlled three cell trial involving 359 infants ages 2 to 5 months. The titer of the D x RRV vaccine was 10(4) and that of the DS 1 x RRV vaccine was 10(5) plaque-forming units/1-ml dose. The vaccines were acceptably reactogenic, each inducing a transient febrile response in fewer than one-third of the vaccinees. Seroconversion by RV enzyme-linked immunosorbent assay IgA antibody was detected in 61 and 75% of the vaccinees receiving a single dose of the serotype 1 or 2 reassortant vaccine, respectively. Efficacy against RV diarrhea was evaluated in two successive epidemic seasons; RV serotype 1 was prevalent in both. Clinical efficacy was observed with both vaccines and was associated with seroconversion after vaccination; considering only such vaccinees both vaccines showed equal efficacy. The overall rates of protection for the two vaccines combined against clinical RV disease in children with seroconversion after vaccination were 92 and 59% in the first and second RV epidemic seasons, respectively. Protection against asymptomatic RV infection, as measured by serologic responses, was 59% in the first season and nil in the second season. It is concluded that each of the reassortant RV vaccines was effective in inducing protection against symptomatic RV disease associated with RV serotype 1.

Administration, Oral↗