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Biomedical subjects

A Roca

Publications and source records attributed to A Roca.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rapid and reproducible deactivation of rhodopsin requires multiple phosphorylation sites.

Efficient single-photon detection by retinal rod photoreceptors requires timely and reproducible deactivation of rhodopsin. Like other G protein-coupled receptors, rhodopsin contains multiple sites for phosphorylation at its COOH-terminal domain. Transgenic and electrophysiological methods were used to functionally dissect the role of the multiple phosphorylation sites during deactivation of rhodopsin in intact mouse rods. Mutant rhodopsins bearing zero, one (S338), or two (S334/S338) phosphorylation sites generated single-photon responses with greatly prolonged, exponentially distributed durations. Responses from rods expressing mutant rhodopsins bearing more than two phosphorylation sites declined along smooth, reproducible time courses; the rate of recovery increased with increasing numbers of phosphorylation sites. We conclude that multiple phosphorylation of rhodopsin is necessary for rapid and reproducible deactivation.

Animals↗
PubMed2000

Humoral immune responses during a malaria vaccine trial in Tanzanian infants.

The development of a malaria vaccine is a priority for improved and sustained malaria control. Optimal use of a vaccine in Africa will only be achieved if it can be delivered through the Expanded Programme of Immunization (EPI). We have completed a trial of the peptide vaccine SPf66 in Tanzanian infants, given alongside the EPI vaccines. This paper describes the humoral responses to SPf66 and the EPI vaccines. A total of 1207 infants were recruited into a two-arm, double-blind, individually randomized placebo-controlled trial of SPf66. The objectives of the trial were to determine the safety, immunogenicity and efficacy of SPf66 and to assess interactions with EPI vaccines when three doses of SPf66 were delivered alongside the EPI vaccines. Cross-sectional surveys were carried out to asses seroconversion rates to the EPI vaccines and the antibody response to SPf66 (NANP)50 and Plasmodium falciparum lysates. Seroconversion rates to EPI vaccines were high and no statistically significant differences in prevalence or titres were found between SPf66 and placebo recipients. IgG antibodies against SPf66 (NANP)50 and whole P. falciparum lysate were present in high titres in mothers of recruited children at the time of birth. Vaccination with SPf66 stimulated a good anti-SPf66 IgG response which declined to preimmunization levels by 2 years of age and which was not associated with protection against clinical malaria. The vaccine induced no IgG antibodies against (NANP)50 or P. falciparum lysates. SPf66 stimulated a humoral immune response when given to very young infants and did not interfere with seroconversion to EPI vaccines. The response to SPf66 was qualitatively different from that seen in older children, in whom SPf66 has been shown to be moderately efficacious. This difference raises concerns about the difficulties of immunizing very young infants who need to be targeted by antimalarial vaccination programs.

Animals↗
PubMed2000

Self-reported sleepiness while driving as a risk factor for traffic accidents in patients with obstructive sleep apnoea syndrome and in non-apnoeic snorers.

The obstructive sleep apnoea syndrome (OSAS) is a condition causing daytime sleepiness and has been related to an increased risk for traffic accidents. However, the evidence linking severity of OSAS to a higher rate of automobile crashes is based on limited data. The aims of this study were to study the traffic accident rate in the last 5 years in patients referred to our sleep clinic because of clinical suspicion of OSAS and to analyse variables related to an increased risk for traffic accidents. A series of 189 consecutive patients with a driving license referred for a sleep study because of OSAS clinical suspicion and a control group (CG) of 40 hospital staff workers who denied snoring, matched for age and sex with the study population, were studied. Patients underwent a full-night polysomnography and both patients and the CG completed a self-answered questionnaire. One hundred and twenty-two patients were diagnosed as OSAS and 67 patients as non-apnoeic snorers (NAS). The self-reported number of accidents was significantly higher in OSAS patients compared with CG. The self-reported number of times off the road was significantly higher in OSAS patients compared with NAS and with CG. Variables associated with an increased risk for traffic accidents were self-reported sleepiness while driving (OR 5, 95%CI 2.3-10.9), having quit driving because of sleepiness (OR 3, 95%CI 1.1-8.6) and being currently working (OR 2.8, 95%CI 1.1-7.7). We conclude that self-reported sleepiness while driving is associated with an increased risk for traffic accidents in OSAS patients and in NAS. We suggest that this symptom can be used to alert patients and to give priority in the sleep clinic for study and treatment.

Accidents, Traffic↗
PubMed1999

[Laparoscopic transsection of Ladd's bands: a new indication for therapeutic laparoscopy in neonates].

Within the last ten years and by the introduction of some new instruments, laparoscopy is a safe and effective method that has been further extended in children. We report our experience in the treatment of laparoscopy on a seven day old newborn affected by malrotation with an intermittent duodenal obstruction. The treatment consisted of a duodenal liberation after the section was easily performed in congenital Ladd's bands. The spiral twists of the small intestine found in the upper gastrointestinal series, disappeared in a new study done after surgery. We consider this operation as a new indication for an operative laparoscopy. It allows a good visualization of this congenital abnormality, and it is easy to perform with a significantly reduced operative trauma.

Duodenal Obstruction↗
PubMed1998

Rectal drainage: unusual evolution of a psoas abscess.

We report two cases of primary psoas abscess in two patients of 15 months and 4 years of age. As the first case showed the natural history of this process the second one was large enough to produce a huge ureterohydronephrosis and to drain through the rectal wall to the rectum spontaneously, although this natural way did not achieve complete drainage. Both were treated by open drainage and systemic antibiotics with good response. They were discharged at the 7th and 12th postoperative day. 5 months later no complication has come up. Etiological, clinical and therapeutic aspects of this unusual pathology are reviewed.

Child, Preschool↗
PubMed1998

Long-term efficacy of dietary weight loss in sleep apnoea/hypopnoea syndrome.

Weight loss is associated with clinical improvement in sleep apnoea/ hypopnoea syndrome (SAHS). The aim of this study was to ascertain whether the therapeutic efficacy of dietary weight loss is maintained in the long-term. From a total of 216 overweight SAHS patients treated by only a weight reduction programme, 24 cured by this method (apnoea/hypopnoea index (AHI) at diagnosis 443+/-27.8, after weight loss 3+/-3.1) were re-evaluated after a mean (+/-SD) period of 94.3+/-27.4 months post-cure. No correlation was found between changes in AHI and body mass index experienced by each patient in the two phases of the study (diagnosis to cure and cure to long-term follow-up), r=0.29, p=0.156, demonstrating a marked intra-individual variability. Six of the 13 patients who maintained their weight presented recurrence of SAHS (AHI 40.5+/-24.1) as did eight of the 11 who had regained weight (AHI 44.3+/-23.). Weight maintenance was more frequent among patients who had continued to attend periodic appointments, 10/11 versus 3/13 (p<0.001). In conclusion, weight-loss efficacy is maintained in the long-term in some sleep apnoea/hypopnoea syndrome patients. This study indicates the need for periodic follow-up of these patients as a reinforcement for weight maintenance and for early detection of the reappearance of sleep apnoea/hypopnoea syndrome.

Adult↗
PubMed1997

Results at 43 months' follow-up of a double-blind, randomized, prospective clinical trial using intravesical interferon alpha-2b in the prophylaxis of stage pT1 transitional cell carcinoma of the bladder.

OBJECTIVES: To assess the intravesical efficacy of 60 million units of interferon (IFN) alpha-2b in preventing recurrences of Stage pT1 transitional cell carcinoma of the bladder, as well as to assess its local and systemic toxicity. METHODS: A total of 90 patients were included in a double-blind, randomized, prospective clinical trial and divided into two groups of 45 patients. After complete transurethral resection, 60 million units IFN alpha-2b was instilled in one group; in the other, double-distilled water was used. The therapeutic regimen consisted of weekly instillation for 12 weeks, followed by once-monthly instillation until patients had completed 1 year of treatment. RESULTS: Only 78 patients were evaluable. After 12 months of follow-up, the relapse rate was 28.2% (11 of 39) for the IFN group and 35.8% (14 of 39) for the control group (P = NS). After 43 months (range 9 to 67), relapse rates were 53.8% (21 of 39) and 51.2% (20 of 39), respectively (P = NS). Progression, mortality, and local or systemic toxicity were similar in both groups. Flu-like syndrome was not reported. CONCLUSIONS: At the dose used in this study, IFN alpha-2b proved ineffective in the prophylaxis of Stage pT1 transitional cell carcinoma of the bladder compared with a control group. Toxicity was virtually absent.

Administration, Intravesical↗
PubMed1997

[The prolapse of the rectum. Treatment with fibrin adhesive].

Injection of sclerosing solutions into the rectal submucosa or into the perirectal space is one of the many therapies designed to correct rectal prolapse. Since 1994, four patients affected with this condition have been treated with fibrin adhesive percutaneous injection. Up to now, this product had not been used to this aim. Age range was from 1 month to 8 years. The medium duration of prolapse prior to therapy was 19 months and three of them had an associated pathology (myelomeningocele, cystic fibrosis and severe psychomotor retardation). There were no post-injection complications. In one patient with an irreducible prolapse an anus encirclement with a rectal tube was associated. Except for this patient, the whole process take less than 24 hours. With a medium follow up of 11 months this therapy has resulted effective in three of our four patients. It has failed in a girl with severe psychomotor retardation.

Child↗
PubMed1997

[Our experience in portal cavernomatosis in childhood: cross-sectional study and analysis of results].

A retrospective and transversal study of our patients with portal cavernomatosis is developed, with the aim of comparing the evolution and the present status of the patients that have undergone different therapeutical approaches. Between 1975 and 1995, 15 patients with portal cavernomatosis have been treated. Personal history, signs and symptoms at the moment of diagnosis, and treatment were analyzed. Now, the controls have been made by physical examination and ECO-Doppler of the espleno-portal system. In 6 cases the absence of bleeding made surgery unnecessary. In the 9 patients with digestive haemorrhage, it could be controlled pharmacologically, with a later surgical approach. Now, all non-operated and 6 operated patients show splenomegaly, without bleeding. The ECO-Doppler shows colateral flow, the splenomegaly in the non-operated and the surgical shunts and the hepatofugal circulation in the operated patients. Looking at our results, we believe that prophylactic surgery is not indicated. In those cases of digestive bleeding, surgery after the complete resolution of the acute disease shows good results at a short and long term.

Child, Preschool↗
PubMed1996

Translocation and aggregation of hepatic glycogen synthase during the fasted-to-refed transition in rats.

Changes in the activation state and intracellular distribution of liver glycogen synthase have been studied during the fasted-to-refed transition in rats. Glycogen synthase activity and activation state were measured in supernatants and pellets obtained after centrifugation of liver homogenates at 9200 g. Upon refeeding, the glycogen synthase activity ratio increased, in a time-dependent manner, in both fractions. The total activity of the enzyme decreased in supernatants and was quantitatively recovered in the pellets. Therefore, refeeding induced both the activation of glycogen synthase and its translocation from the soluble to the pelletable fraction. Immunocytochemical evidence indicates that refeeding induced the formation of clusters of glycogen synthase, which were recovered in the 9200 g sediments. However, the enzyme clusters did not locate with the glycogen particles in the pelletable fraction. The glycogen synthase activation state responded almost as an of-off switch to changes in the intracellular glucose 6-phosphate concentration in the range 0.2-0.3 mM. The amount of enzyme present in the pellets correlated linearly with the intracellular glucose 6-phosphate levels. These results indicate that glucose 6-phosphate is the key signal for both the activation and changes in intracellular localization of hepatic glycogen synthase in vivo.

Animals↗
PubMed1996

Direct activating effects of dexamethasone on glycogen metabolizing enzymes in primary cultured rat hepatocytes.

The direct effects of dexamethasone on glycogen synthase and phosphorylase and glycogen content have been investigated in primary cultured rat hepatocytes. Dexamethasone induced the transient translocation of glycogen synthase from the soluble to the 10000xg pelletable fraction and the activation of this enzyme, although more significant, longer-standing activation was achieved in the pelletable fraction. Neither total glycogen synthase content nor glycogen synthase mRNA levels were modified. Dexamethasone also caused the sustained activation (up to 6h) of glycogen phosphorylase, which was not accompanied by an increase in its mRNA level. Glycogen cell content and the incorporation of (14C) glucose into glycogen decreased after dexamethasone treatment. The data show that dexamethasone, unlike other glycogenolytic hormones, at concentrations of 10 nM or higher, stimulate hepatocyte glycogenolysis without inducing the inverse coupling of synthase and phosphorylase. The co-existence of active forms of both glycogen synthase and phosphorylase promoted by dexamethasone leads to a situation that is analogous to that of the fasted liver.

Animals↗
PubMed1996

Nasal continuous positive airway pressure with supplemental oxygen in coexistent sleep apnoea-hypopnoea syndrome and severe chronic obstructive pulmonary disease.

The objective of our study was to assess the application of nasal continuous positive airway pressure (nCPAP) with supplemental oxygen for correction of upper airway obstructive episodes and hypoxaemia during sleep in stable patients with sleep apnoea-hypopnoea syndrome (SAHS) and severe chronic obstructive pulmonary disease (COPD). Ten male patients with symptomatic SAHS and severe COPD (forced expiratory volume in one second < 50% of predicted) were studied for three consecutive nights. Diagnostic polysomnography was performed the first night and repeated with increasing nCPAP levels, with and without supplemental oxygen on the second and third nights, respectively. Diagnostic polysomnography showed: mean (SD) apnoea-hypopnoea index 41 (22) events.h-1; mean arterial oxygen saturation (Sa,O2) was 86 (2)% and mean desaturation nadir was 81 (4)% during non-rapid eye movement (nREM) sleep and 80 (7)% and 73 (9)%, respectively during REM sleep. The application of nCPAP during the second night corrected apnoeas and hypopnoeas, but mean Sa,O2 remained < 90% in all patients. With the addition of oxygen at a flow of 1.5 L.min-1 at suboptimal nCPAP levels, we observed an increase in apnoea frequency, persistence of apnoeas at nCPAP levels which eliminated them when no supplemental oxygen was administered, and longer duration of apnoeas and hypopnoeas. However, when the effective nCPAP level of the second night was reached with supplemental oxygen during the third night, its efficacy in eliminating apnoeas and hypopnoeas was maintained and, furthermore, all patients presented Sa,O2 > 90%, with no greater hypercapnia cardiac arrhythmias. We conclude that nasal continuous positive airway pressure with supplemental oxygen constitutes a practical therapeutic alternative for hypoxic patients with sleep apnoea-hypopnoea syndrome and chronic obstructive pulmonary disease.

Aged↗
PubMed1996

[Prenatal diagnosis of biliary atresia associated with choledochal cyst].

We report a case of biliary atresia promptly detected by its association with a choledochal cyst, prenatally diagnosed at 20 weeks' gestation. The baby was operated at 14 days of life. A choledochal cyst was found and fibrosis of the extrahepatic bile ducts was also noted. So, excision of the choledochal cyst and a Roux-en-Y porto-jejunostomy was done. Nine months later, despite an appropriate biliary drainage, echographic and histological changes compatible with liver cirrhosis have been detected. Including this one, six cases have been reported.

Biliary Atresia↗
PubMed1995

Development of an observation method for assessing pain behaviors in children with juvenile rheumatoid arthritis.

OBJECTIVE: To develop an observation method for assessing pain behaviors in children with juvenile rheumatoid arthritis (JRA). METHODS: Thirty children with JRA performed a standardized sequence of activities for video recording, and correlations between the pain behaviors observed on the videotapes and established measures of pain, depression, and functional disability were determined. RESULTS: Pain behaviors were reliably observed (kappa coefficients 0.53-0.79). Total pain behaviors were significantly correlated with subjective reports of pain (r = 0.50) and disability levels (r = 0.64). These behaviors were not significantly associated with children's depression ratings (r = 23). CONCLUSION: The results indicate that the behavioral observation method provides a reliable and valid measure of pain associated with JRA. Measurement of pain behaviors may be especially useful in treatment outcome studies because these behaviors are relatively independent of depression.

Adolescent↗
PubMed1994

Physical mapping of 5S rDNA reveals a new locus on 3R and unexpected complexity in a rye translocation used in chromosome mapping.

Using fluorescence in situ hybridization (FISH) with probe pScT7, three different 5S rDNA loci were detected in the satellite of rye chromosome 1R (5SDna-R1) and in the short arms of chromosomes 3R (5SDna-R3) and 5R (5SDna-R2) respectively. All three loci showed polymorphism for the hybridization signal intensity. In order to determine the localization of these rye 5S rDNA multigene loci with higher precision within the corresponding chromosome arms, the probe pScT7 was physically mapped by FISH in relation to the following five translocations (Wageningen Tester Set): T850W (1RS/4RL), T248W (1RS/6RS), T273W (1RS/5RL), T305W (2RS/5RS) and T240W (3RS/5RL). Accurate physical maps of the translocation breakpoints had previously been made using electron microscope analysis of spread pachytene synaptonemal complexes of heterozygotes for the different translocations. The results indicate that locus 5SDna-R3 is located between the breakpoint of translocation T240W and the telomere, whereas locus 5SDna-R2 is located between the breakpoint of translocation T305W and the centromere, the hybridization of probe pScT7 on T305W translocated chromosomes demonstrating the complex nature of this translocation. On the other hand, the simultaneous detection of probes pScT7 and pTA71 (18S-5.8S-26S rDNA) with two different fluorochromes, indicated that the breakpoints of translocations T850W and T248W are located between loci Nor-R1 and 5SDna-R1.

Chromosome Mapping↗
PubMed1994

Neonatal survival after preterm premature rupture of membranes secondary to first trimester chorionic villus sampling.

A case of preterm premature rupture of membranes (PROM) secondary to first trimester chorial biopsy is described. The newborn survived and physical and psychological development was normal at 1 year of age. On review of the literature, different attitudes may be found with regard to the treatment of PROM: some authors prefer expectant management while others defend extraction of the fetus when reasonable maturity is reached. In both cases the outcome is usually poor for the fetus.

Adult↗
PubMed1994

Recurrent tracheoesophageal fistula treated with fibrin glue.

Recurrent tracheoesophageal fistula (RTF) after repair of esophageal atresia with tracheoesophageal fistula is a serious complication, with the need for a second operation. The mortality rate is high. The authors report on the eradication of RTF using fibrin glue.

Bronchoscopy↗