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Biomedical subjects

R Alvarado

Publications and source records attributed to R Alvarado.

At least 19 recordsLinked to original sources
PubMed2006

Pneumatic retinopexy: success rate and complications.

AIM: To evaluate the success rate and complications of pneumatic retinopexy performed at a university hospital and to identify which patients are best suited for pneumatic retinopexy. METHODS: This was an interventional case series. Retrospective review of 61 patients who had pneumatic retinopexy performed by two retina surgeons at two University of California, San Francisco hospitals between 1998 and 2004. Patients who had been treated for rhegmatogenous retinal detachment (RRD) with pneumatic retinopexy were identified by reviewing operative reports and billing records. The primary outcome measure was anatomical reattachment of the retina with a single intervention. Secondary outcome measures included postoperative visual acuity and postoperative complications. RESULTS: 33 of 61 (54%) cases were successful with a single procedure. 40 of 61 (66%) cases were successful with repeat injection of gas or laser retinopexy alone. All cases had anatomical success at final follow up. Age, myopia, lens status, and number of breaks were not proved to be risk factors for failure. The average duration of follow up was 15 months. CONCLUSIONS: In this case series, pneumatic retinopexy was less effective for the repair of RRD than most large published reports. However, failure of pneumatic retinopexy followed by scleral buckle or pars plana vitrectomy did not negatively influence visual acuity at final follow up.

Adult↗
PubMed2005

The impact of preoperative weight loss in patients undergoing laparoscopic Roux-en-Y gastric bypass.

BACKGROUND: Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is a widely performed bariatric operation. Preoperative factors that predict successful outcomes are currently being studied. The goal of this study was to determine if preoperative weight loss was associated with positive outcomes in patients undergoing LRYGBP. METHODS: A retrospective analysis was performed of all patients undergoing LRYGBP at our institution between July 2002 (when a policy of preoperative weight loss was instituted) and August 2003. Outcome measures evaluated at 1 year postoperatively included percent excess weight loss (EWL) and correction of co-morbidities. Statistical analysis was performed by multiple linear regression. P<0.05 was considered significant. RESULTS: The study included 90 subjects. Initial BMI ranged from 35.4 to 63.1 (mean 48.1). Preoperative weight loss ranged from 0 to 23.8% (mean 7.25). At 12 months, postoperative EWL ranged from 40.4% to 110.9 % (mean 74.4%). Preoperative loss of 1% of initial weight correlated with an increase of 1.8% of postoperative EWL at 1 year. In addition, initial BMI correlated negatively with EWL, so that an increase of 1 unit of BMI correlated with a decrease of 1.34% of EWL. Finally, preoperative weight loss of >5% correlated significantly with shorter operative times by 36 minutes. Preoperative weight loss did not correlate with postoperative complications or correction of co-morbidities. CONCLUSIONS: Preoperative weight loss resulted in higher postoperative weight loss at 1 year and in shorter operative times with LRYGBP. No differences in correction of co-morbidities or complication rates were found with preoperative weight loss in this study. Preoperative weight loss should be encouraged in patients undergoing bariatric surgery.

Adult↗
PubMed2003

Effect of electrical stimulation of the baso-lateral amygdala nucleus on defensive burying shock probe test and elevated plus maze in rats.

In the present report, the putative effect of a single electrical stimulation (75, 150 or 300 microA) to the baso-lateral amygdala (BLA) nucleus was assessed in shock probe defensive burying behavior test (DB) and elevated plus maze (EPM). These models have been used for measuring anxiety levels and screening putative anxiolytic compounds. A group of 28 rats were randomly divided for the following experimental conditions: Control-control, sham-operated, BLA stimulated groups: 75, 150 and 300 microA tested for DB. The cumulative defensive burying in a 15 min-test, the latency of burying, the number of shock received and the height of the bedding material in the probe were recorded. Another group of 28 individuals was also randomly distributed for the following experimental conditions: Control-control, sham-operated, BLA stimulated animals: 75, 150, 300 microA and tested in the EPM. The time the subjects spent in the open arms, the crosses and the faeces number excreted during the test were recorded. Decreased levels of defensive burying were observed in 75, 150 and 300 microA stimulated groups. The 150 and 300 microA groups reached statistical significance. The fact that 300 microA stimulated group showed statistically significant increase in the latency of defensive burying, in the number of shock received and decreased amount in bedding material suggests a sedative action of electrical stimulation. Increased time in the open arms and augmented number of crossings in 150 microA group was observed. No changes in the number of faeces were observed in any group. The evidence supported the notion of an inhibitory amygdaline mechanism triggered by sub-threshold electrical stimulation.

Amygdala↗
PubMed2002

Laparoscopy may be lowering the threshold to operate on patients with suspected appendicitis.

BACKGROUND: Although several randomized trials have compared postoperative outcomes in patients undergoing open and laparoscopic appendectomy, few have examined whether laparoscopy has affected preoperative decision making. We hypothesized that surgeon enthusiasm for laparoscopic appendectomy would lower the threshold to operate on patients with possible appendicitis. To examine this question we designed a retrospective cohort study in the setting of a tertiary care medical center. METHODS: We studied a consecutive series of 130 patients taken to the operating room with preoperative diagnoses of appendicitis between 1 January 1997 and 31 December 1999. We excluded pregnant patients, those under 18 or over 75, those admitted electively for chronic symptoms, and those undergoing appendectomy incidental to another procedure. Measures included the proportion of patients with normal appendices or acute appendicitis (perforated and nonperforated), as determined from the pathology report. Other clinical and demographic data were obtained by review of the medical records. RESULTS: During the study period, 87 patients (67%) underwent open appendectomy and 43 patients (33%) underwent laparoscopic appendectomy. Women were more likely to receive the laparoscopic approach than men (43% vs 24% p = 0.021). Preoperative use of advanced imaging tests (computed tomography or ultrasound) was more prevalent in the laparoscopic group (40% vs 30%, p = 0.271). Patients undergoing the laparoscopic procedure were considerably less likely to have acute appendicitis than those undergoing an open one (67% vs 92%, p <0.001). However, among patients with confirmed appendicitis, those undergoing laparoscopic surgery were less likely to be perforated than those who had an open procedure (4.6% vs 25% p = 0.004). CONCLUSION: At our hospital, the availability of the laparoscopic approach to appendectomy may have lowered the threshold to operate on patients with possible appendicitis, as reflected in higher negative exploration rates and lower rates of perforated appendicitis.

Acute Disease↗
PubMed2001

Differential effects of NMDA antagonists microinjections into the nucleus reticularis pontis caudalis on seizures induced by pentylenetetrazol in the rat.

It has been shown that NMDA antagonists block the tonic but not the clonic component of seizures when they are injected in the oral region of the rat pontine reticular formation (PRF). The participation of the caudal PRF in the effects of NMDA antagonists upon the tonic and the clonic components of generalized seizures induced by pentylenetetrazol (PTZ) is unknown. The aim of the present study was to evaluate the effects of unilateral microinjections of competitive and non-competitive NMDA antagonists, 2-amino-7-phosphonoheptanoic acid (AP-7) and dizocilpine (MK-801), respectively, into the nucleus reticularis pontis caudalis of the rat PRF upon seizures induced by PTZ (70 mg/kg i.p.). MK-801 induced a dose-related decrease both in the incidence of generalized tonic-clonic seizures (GTCS) and in the presence of spikes in the EEG. MK-801 also increased GTCS latency. On the contrary, AP-7 did not have effects on GTCS. Interestingly, it induced ipsilateral circling behavior. These results suggest that in the caudal region of the rat PRF only non-competitive NMDA antagonists should block the generation of tonic and clonic components of generalized seizures.

2-Amino-5-phosphonovalerate↗
PubMed1999

Progesterone microinjections into the pontine reticular formation modify sleep in male and female rats.

It has been reported that progesterone (P4) induces changes in sleep, but the brain regions involved in these actions are unknown. We studied the effects of P4 microinjections into the pontine reticular formation (PRF) upon rat sleep. Intact adult male and ovariectomized female rats were unilaterally injected with P4 into the PRF and the sleep-waking cycle was recorded for 6 h. P4 (1.0 and 5.0 microg/0.2 microl) did not modify sleep, but at a higher dose (7.5 microg/0.2 microl) it produced a marked decrease in rapid eye movement sleep (REM) latency in both male (55%) and female (63%) rats. A non-significant increase in the number of REM episodes was observed after P4 administration. These findings suggest that P4 should participate in the mechanisms related to REM initiation in the rat through its effects in the PRF.

Animals↗
PubMed1999

Integrated maternal and infant health care in the postpartum period in a poor neighborhood in Santiago, Chile.

An integrated postpartum health-care program was established by the Consultorio San Luis de Huechuraba (CSLH), a nongovernmental organization in a neighborhood of extreme poverty in Santiago, Chile. The main components were education, maternal and infant health care, support for the mothers, and active participation of women from the community served. The program was evaluated through indicators of contraceptive use, breastfeeding performance, infant growth and health, and a qualitative assessment of women's satisfaction. Controls were women of similar characteristics attending the nearby public clinic. Acceptability of contraceptive methods was similar but contraceptive options differed between clinics. The total number of pregnancies and of respondents lost to follow-up was significantly higher for the public clinic than for the CSLH. Breastfeeding duration was significantly longer and infant growth and health were found to be significantly better at the CSLH than at the public clinic. Women valued being treated with respect, receiving education and support, and being offered timesaving services and wider contraceptive choices at the CSLH. This study demonstrates that such interventions are possible for poor communities, providing significant advantages for women and children.

Adult↗
PubMed1998

Degree of hypercoagulability and hyperfibrinolysis is related to organ failure and prognosis after burn trauma.

Severely burned patients often present a hypercoagulability situation. However, its magnitude, time course, and relationship with organ failure and outcome remains to be established. Forty-three patients were studied on the first and seventh day after burn for hypercoagulability and fibrinolysis parameters. A hypercoagulability and hyperfibrinolysis state was found the first day after burn demonstrated by high levels of activated factor VII (VIIa, p<0.01), thrombin-antithrombin III complex (TAT, p<0.01), tissue plasminogen activator (t-PA, p<0.001) and D dimer (DD, p<0.01) and low levels of antithrombin III (ATIII, p<0.01), protein C (PC, p<0.01), plasminogen (PG, p<0.001) and alpha2 antiplasmin (AP, p<0.001). A paradoxical coexisting hypofibrinolysis was found as suggested by a low global fibrinolytic activity in the euglobulin plasma fraction fibrin plate assay (FA, p<0.01) and high levels of tissue plasminogen activator inhibitor type 1 (PAI-1, p<0.01). On day 7, a less marked hypercoagulability situation was found, with low ATIII (p<0.01) and PC (p<0.01), persisting the hypofibrinolytic situation observed on the first day. Non-survivors (NS) showed higher levels of VIIa (p<0.01), TAT (p<0.05) and t-PA (p<0.05), and lower levels of ATIII (p<0.05), PC (p<0.05) and AP (p<0.001) than survivors (S) on the first day. Also, there was a positive correlation of Marshall organ failure score with ATIII, (r2=0.49, p<0.001), PC, (r2=0.14, p<0.045) and PG levels, (r2=0.41, p<0.0003). Severely burned patients show a state of transient disseminated intravascular coagulation, related to the development of organ failure and outcome.

Adult↗
PubMed1998

Infectious agents associated with diarrhoea of calves in the canton of Tilarán, Costa Rica.

A case-control study of calves under 3 months of age was carried out by weekly visits to 15 farms in the canton of Tilarán, Costa Rica. Most farms were dedicated to beef or dual-purpose (DP) production. Faecal samples were collected over a 6-month period from a total of 194 calves with clinical signs and from 186 animals without clinical signs of diarrhoea as assessed by a scoring system. The samples were investigated for the presence of viruses, bacteria and parasites. Torovirus was detected for the first time in Costa Rica and was present in 14% of calves with diarrhoea and in 6% of the controls. Coronavirus and Rotavirus were less frequently encountered in either one of the groups (in 9 and 7% of scouring calves and in 1 and 2% of controls, respectively). Escherichia coli was detected in 94% of all the faecal samples, but isolates from only three samples from calves with diarrhoea contained the K99 antigen. Similarly, Salmonella was found only in scouring calves. Cryptosporidium oocysts were detected in animals with signs of diarrhoea, while other coccidia oocysts, Strongylida and Strongyloides eggs were frequently found in animals both with and without diarrhoea. A conditional logistic regression (CLR) analysis to compare healthy and scouring calves showed a significant difference with regard to the presence of Torovirus, Rotavirus and Coronavirus.

Animals↗
PubMed1996

Effects of regional GABAergic blockade of the striatum on memory consolidation.

The prediction was made that blocking the action of gamma-aminobutyric acid (GABA) in different regions of the striatum, through local injection of picrotoxin, would produce differential amnestic effects. Rats were trained in an inhibitory avoidance task, and a retention test was carried out 24 h later. Posttraining injection of picrotoxin (1 microgram/1 microliter) into posteroventral and lateral regions produced strong amnesia; an intermediate degree of impairment was found when delivered at dorsomedial regions; and no retention deficit was found when given to the ventromedial aspect of the anterior striatum. In sum, the retention impairments were consistently higher in posterior and lateral striatal regions than in the anterior and medial regions. The present findings support the concept that striatal GABAergic activity is involved in memory functions and also provide further evidence of neurochemical heterogeneity within the striatum regarding memory consolidation.

Animals↗
PubMed1993

[Gyneco-obstetric aspects in women developing postpartum depression].

The relationship between different variables was studied related to pregnancy, labor, puerperium, newborn and breast-feeding with the development of a depressive disorders during pregnancy, in a sample of 125 pregnant women. No relationship it's found with the presence of disease during the gestation period, except urinary tract infection. The same happens with other variable of labor, puerperium and newborn, Nevertheless, the major stress situations (urgent cesarean section, use of anesthesia during labor, diseases of the newborn, etc.) systematically present a higher incidence of depression. It is observer a relationship between the development of a depressive disorders and a decrease of the natural lactation period.

Adolescent↗
PubMed1993

[Depressive disorders during pregnancy and associated factors].

A group of 125 pregnant women is studied that is under the control of 2 urban and 1 rural health clinic, were it was found an incidence of 29% of depressive disorders. It is observed that three aspects are strongly related with this disorders: unwanted pregnancy, unsatisfactory couple relationships and personal back-ground with depression. A working model is proposed that seeks to comprehend this phenomenon in its entirety.

Adolescent↗
PubMed1992

Sexual behavior enhances postictal behavioral depression in kindled rats: opioid involvement.

Past research has demonstrated brain opioid and GABA release in response to ejaculation. In the present study we evaluated the potential role of these neurotransmitters in the postictal behavioral depression (PBD), after-discharge (AD) duration, and seizure intensity in rats kindled in the medial preoptic area (MPOA) and amygdala (AMG). The PBD, the AD duration and the seizure intensity were measured after a standard kindling stimulus and after a standard kindling stimulus applied 2 min after ejaculation. The PBD was significantly increased when the animals were stimulated 2 min after ejaculation. This increase was found in MPOA- but not in AMG-kindled rats. Ejaculation had no effect on AD duration or seizure intensity. Naloxone administration before the initiation of sexual behavior completely blocked the increase in PBD in MPOA-kindled rats. It is suggested, by indirect evidence, that opioid release during sexual behavior is added to the release associated with kindled seizures, increasing the duration of the PBD. Since sexual behavior lacked effect on AD duration or seizure intensity, no evidence could be found suggesting that functionally relevant amounts of GABA are released during this behavior.

Amygdala↗
PubMed1991

Microinjections of muscimol and bicuculline into the pontine reticular formation modify the sleep-waking cycle in the rat.

The role of gamma-aminobutyric acid (GABA) in the sleep-waking cycle was evaluated by means of microinjections of muscimol and bicuculline into the rat pontine reticular formation (PRF). Muscimol (20 ng) produced a marked increase in wakefulness (70%), a decrease in slow-wave sleep (SWS) (35%) and a remarkable delay in the onset of both SWS and paradoxical sleep, without modifying the percentage of the latter. Bicuculline (4 ng) shortened SWS latency by about 70%. These results suggest that GABAergic transmission in the PRF is involved in the regulation of sleep-waking cycle in the rat.

Animals↗
PubMed1991

Release of acetylcholine and GABA, and activity of their synthesizing enzymes in the rat pontine reticular formation.

The aim of this study was to obtain neurochemical information on the possible role of acetylcholine (ACh) and gamma-aminobutyric acid (GABA) as neurotransmitters in the pontine reticular formation (PRF). We studied the uptake of labeled choline and GABA, as well as the release of this amino acid and of ACh, in PRF slices of the rat. In addition, choline acetyltransferase, acetylcholinesterase and glutamate decarboxylase activities were assayed in PRF homogenates. The uptake of GABA was strictly Na(+)-dependent, whereas choline uptake was only partially Na(+)-dependent. The release of both ACh and GABA was stimulated by K(+)-depolarization, but only the former was Ca(2+)-dependent. Choline acetyltransferase activity in the PRF was 74% of that in the striatum, whereas acetylcholinesterase activity was considerably lower. Glutamate decarboxylase activity in the PRF was about half that observed in the striatum. These findings support the possibility that both ACh and GABA may act as neurotransmitters in the rat PRF.

Acetylcholine↗
PubMed1991

Clinical and microbiological patterns of adults with periodontitis.

Although current data suggest that periodontitis may actually be multiple diseases each with varying responses to therapy, little evidence exists to support this theory in adult patients. This report describes the design and initial findings of a longitudinal field trial involving the diagnosis and treatment of adult and refractory periodontitis patients in private practice. Adult patients (N = 221) who met specific clinical criteria were selected from the private practices of 22 periodontists. Clinical characteristics were recorded and subgingival plaque samples were sent to microbiology laboratories at either UCLA or The University of Texas Health Science Center at San Antonio (UTHSCSA). Samples were processed according to protocols standardized between the 2 centers. Five different combinations of the initial clinical and microbial findings were evaluated for patterns in the data by means of cluster analysis. Plaque, bleeding on probing, bone loss scores, probing depth distributions, and microbial findings produced multiple cluster solutions. Solutions involving 6 clusters explained 39.4% to 76.4% of the variation between patients and produced ratios for variation between clusters to variation within clusters of 5.2 to 15.3. The optimal cluster solution incorporated both clinical and microbial findings, with some clusters characterized by high plaque and moderate bleeding on probing and bone loss, whereas others had low plaque but high bleeding on probing and bone loss. Microbial findings of each cluster exhibited distinct patterns with some clusters having a high prevalence (83% to 100%) of specific target bacterial species while other clusters had an absence of these species.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Medial preoptic area kindling induces sexual behavior in sexually inactive male rats.

In the present experiments, sexually experienced and non-copulating male rats were kindled in the medial preoptic area (MPOA) or the amygdala (AMG) with the purpose to investigate if the widespread modification of brain function produced by kindling induces sexual behavior in non-copulating rats and if kindling facilitates sexual behavior in copulating rats. Since kindling in the MPOA has been little studied, a description of this phenomenon is also presented. The animals were stimulated 4 times daily on odd days and sexual behavior monitored on even days. The results showed that the MPOA required higher stimulus intensity to elicit an afterdischarge (AD) than the AMG. The AD duration was significantly longer in animals kindled in the MPOA than in animals kindled in the AMG. No difference was found in the development of kindling between these brain structures. Kindling had no effect upon sexual behavior in copulating rats. In contrast, MPOA kindling induced copulation in non-copulating male rats. Seven out of 9 animals displayed sexual behavior. No significant facilitation was observed after AMG kindling in non-copulating male rats. Furthermore, the sexual behavior displayed by the previously non-copulating MPOA kindled rats was similar to the sexual behavior displayed by sexually experienced animals. It is proposed that sexual behavior is facilitated in these male rats by local neural changes produced by kindling.

Animals↗