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Biomedical subjects

A Contreras

Publications and source records attributed to A Contreras.

At least 55 records · Page 3Linked to original sources
PubMed1999

Proficiencies of three anaerobic culture systems for recovering periodontal pathogenic bacteria.

Anaerobic culture is employed routinely in the primary isolation of periodontal pathogenic bacteria. However, little or no data exist on the relative abilities of the Coy anaerobic chamber (Coy Laboratory Products, Grass Lake, Mich.), the GasPak (Becton Dickinson Microbiology Systems, Cockeysville, Md.), and the AnaeroPack (Mitsubishi Gas Chemical America, Inc., New York, N.Y.) systems to grow important periodontal species, including Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Bacteroides forsythus, Eubacterium species, Campylobacter species, Fusobacterium species, and Peptostreptococcus micros. A total of 78 specimens from advanced periodontitis lesions were collected anaerobically, plated on enriched blood agar medium, and incubated at 35 degrees C for 5 to 7 days in each anaerobic culture system. The three culture systems were equally efficient in isolating Porphyromonas gingivalis and Prevotella intermedia/nigrescens. The Coy anaerobic chamber yielded the highest proportional recoveries of Campylobacter (P = 0.0001; nonparametric analysis of variance) and Eubacterium (P = 0.009). The Coy anaerobic chamber and the GasPak system demonstrated higher proportional recoveries of Bacteroides forsythus (P = 0.0006) and Peptostreptococcus micros (P = 0.0001) than the AnaeroPack system. The AnaeroPack system was most efficient in growing Fusobacterium species (P = 0.0001). Overall, the Coy anaerobic chamber and the GasPak system showed the highest proportional recoveries of putative periodontal pathogens, but the recoveries by the various anaerobic test systems varied considerably from sample to sample.

Adult↗
PubMed1999

Chicago community-based asthma intervention trial: feasibility of delivering peer education in an inner-city population.

The most effective means of educating children with asthma and their families has not been clearly demonstrated in previous studies. Peer education is uniquely suited to the complex problems encountered in underserved populations. The purpose of this study was to show the feasibility of delivering a peer education program for children with asthma and the effect of the program on indoor allergen levels in an inner-city population in Chicago. Overall, the program was well received. Baseline allergen levels were consistent with some previous studies in showing low levels of mite allergens and high levels of cockroach allergens, with 79.6% of samples having levels > 8 U/g. A total of 28.2% of samples had cat allergen levels > 2 microg/g, although only 9.7% of homes had cats, confirming previous reports that cat allergen is ubiquitous. Mold levels were seasonal, with the highest levels in the summer. Results from this study suggest that intervention programs should focus more on elimination of cockroaches than was previously appreciated, while minimizing the use of pesticides, and on identification of the sources of cat allergen. Structural and psychosocial issues in homes need to be addressed in future studies. This study has demonstrated the feasibility of delivering peer education in a inner-city population and highlighted the need for comprehensive intervention strategies addressing complex issues facing underserved neighborhoods.

Adolescent↗
PubMed1999

Relationship between herpesviruses and adult periodontitis and periodontopathic bacteria.

BACKGROUND: Various mammalian viruses and specific bacteria seem to play important roles in the pathogenesis of human periodontitis. This study examined the relationship between subgingival herpesviruses and periodontal disease and potential periodontopathic bacteria in 140 adults exhibiting either periodontitis or gingivitis. METHODS: A nested-polymerase chain reaction (PCR) method determined the presence of Epstein-Barr virus type 1 and type 2 (EBV-1, EBV-2), human cytomegalovirus (HCMV), and herpes simplex virus (HSV) and a 16S rRNA PCR detection method identified Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Bacteroides forsythus, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola. RESULTS: Using a logistic analysis, EBV-1 showed significant positive association with P. gingivalis (odds ratio [OR] 3.37), and with coinfections of P. gingivalis and P. intermedia (OR 4.03); P. gingivalis and B. forsythus (OR 3.84); P. gingivalis and T. denticola (OR 4.17); P. gingivalis, B. forsythus, and T. denticola (OR 4.06); and P. gingivalis, P. nigrescens, and T. denticola (OR 3.29). EBV-1 also showed positive association with severe periodontitis (OR 5.09), with increasing age (OR 1.03), and with periodontal probing depth at the sample sites (OR 1.77). HCMV was positively associated with coinfections of P. gingivalis and P. nigrescens (OR 3.23); P. gingivalis, B. forsythus, and P. nigrescens (OR 3.23); and P. gingivalis, P. nigrescens, and T. denticola (OR 2.59); with severe periodontitis (OR 4.65); and with age (OR 1.03). Patients with mixed viral infections revealed significant associations with P. gingivalis (OR 2.27), and with coinfections of P. gingivalis and B. forsythus (OR 2.06); P. gingivalis and P. nigrescens (OR 2.91); P. gingivalis, B. forsythus, and P. nigrescens (OR 2.91); and P. gingivalis, P. nigrescens, and T. denticola (OR 2.70) with the clinical diagnosis of slight (OR 3.73), moderate (OR 3.82), or severe periodontitis (OR 4.36), and with probing depth at the sample sites (OR 1.39). HSV and EBV-2 showed no significant associations with any of the variables tested. CONCLUSIONS: The results indicate that subgingival EBV-1, HCMV, and viral coinfections are associated with the subgingival presence of some periodontal pathogens and periodontitis. Herpesviruses may exert periodontopathic potential by decreasing the host resistance against subgingival colonization and multiplication of periodontal pathogens.

Actinobacillus Infections↗
PubMed1999

[Retraction of lower limbs in a female with hyperthyroidism].

We report a 47 years old woman with hyperthyroidism that had a severe tendinous retraction of hips and knees that subsided with propylthiouracil treatment. Electrodiagnosis showed myopathic alterations and muscle strength was moderately reduced. The authors did not find references of a similar condition in patients with hyperthyroidism.

Endocrine System Diseases↗
PubMed1998

Interaction between CO2-mass transfer, light availability, and hydrodynamic stress in the growth of phaeodactylum tricornutum in a concentric tube airlift photobioreactor

The microalga Phaeodactylum tricornutum was grown in a concentric tube airlift photobioreactor. A maximum specific growth rate of 0. 023 h-1 was obtained using a superficial gas velocity around 0.055 m/s. Lower or higher gas flow rates limited the culture performance. To establish if the observed limitation was due to CO2 or to the photosynthetically active irradiance, characteristic times for mixing, mass transfer and CO2 consumption, and the photon flux absorbed by the culture were analyzed. The CO2-gradients in the culture were shown to be responsible for the limitation during the exponential growth phase, and both CO2 and light irradiance were limiting in the linear growth phase. The decrease in specific growth rate relative to the maximum was found to be related to the specific gas-liquid interfacial area, the length scale of the microeddies and the shear rate. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1998

Caprine arthritis-encephalitis in an indigenous Spanish breed of dairy goat.

The presence of caprine arthritis and encephalitis (CAE) in Spain has never been officially acknowledged but it is suspected. Goats have been imported from other European countries with a high prevalence of the disease, mainly France, and they might have introduced the disease into the indigenous goat population. A serological survey of caprine arthritis and encephalitis virus antibodies was carried out in 22 volunteer dairy Murciano-Granadina goat herds; 2513 lactating goats were tested with an agar gel immunodiffusion test, and 12.1 per cent were found to be positive. Five of the herds were free of infection, six had a low prevalence of the disease, five had a medium prevalence and six had a high prevalence. Five seropositive goats with clinical signs of CAE were studied. Macroscopic and microscopic lesions similar to those described for CAE were detected in all five goats and a cytopathic effect typical of CAE virus was observed in primary explant cultures from four of them.

Animals↗
PubMed1998

Comparative study of 2 variants of a modified esophageal transection in the Sugiura-Futagawa operation.

OBJECTIVE: To compare 2 techniques of esophageal transection in our modification of the Sugiura-Futagawa procedure for the treatment of bleeding portal hypertension in low-risk patients who cannot undergo surgery to have shunts placed. DESIGN: A prospective controlled trial comparing 2 variants of transection (classic, complete section of the anterior muscularis externa and whole mucosa; modified, placement of a circumferential running suture without opening the mucosa). SETTING: Academic university hospital. PATIENTS: Eighty-three low-risk patients (Child-Pugh score A and B) with a history of bleeding portal hypertension were operated on (35 classic, 48 modified transections) between 1989 and 1996. Both groups were comparable. MAIN OUTCOME MEASURES: Postoperative dehiscence of the transection was evaluated as well as fistulization, postoperative stenosis, rebleeding, postoperative endoscopic findings, survival, and mortality. RESULTS: Fistulization was observed in 1 (2%) of the patients in the modified group, and dehiscence in 1 patient (2%). In the classic group, 3 (8%) of the patients had dehiscence (relative risk, 2.6) and 1 (2%) of the patients, fistulization. No differences were observed regarding rebleeding (6 patients [6%] vs 5 patients [7%]), postoperative stenosis (4 patients [8%] vs 5 patients [10%]), postoperative endoscopic findings, survival, and mortality (early and late). CONCLUSION: The modified variant of the transection has a lower frequency of postoperative dehiscence, with the same long-term results.

Esophageal and Gastric Varices↗
PubMed1998

Relationships of race and socioeconomic status with prevalence, severity, and symptoms of asthma in Chicago school children.

BACKGROUND: Asthma mortality rates in Chicago are among the highest in the United States, with substantially greater rates in poor and minority populations. How much of the differential can be attributed to differences in prevalence versus severity or access to care has not been determined. OBJECTIVE: To examine rates of asthma prevalence, severity, and symptoms and to explore the relationships of these rates to race and socioeconomic status in a random sample of Chicago school children. METHODS: Self-administered survey. RESULTS: Overall, rates of asthma were higher than previously reported, with 16% of students in the stratified cluster random sample of 3,670 children in the 7th and 8th grades having had asthma. Prevalence rates were significantly higher in schools with >98% African Americans than in other schools, with the highest prevalence rates seen in African American schools in low income neighborhoods. Rates were associated with the percent of African American children in the school and with median income of the school's census tract. Relationships were most consistent with indices of more severe disease. CONCLUSIONS: Asthma prevalence is higher than previously noted, with rates greatest in minority and low income populations. Differences are more striking for measures of severity than for symptoms of wheezing, but are far less than previously reported differences in mortality, suggesting that additional factors, such as differential access to continuous health care, may be affecting high death rates from asthma in Chicago.

Adolescent↗
PubMed1998

Active cytomegalovirus infection in human periodontitis.

This study used the reverse transcription polymerase chain reaction method to determine mRNA transcription of subgingival human cytomegalovirus (HCMV) in six adult and three localized juvenile periodontitis patients. The oligonucleotide primers targeted the major capsid protein gene to determine active HCMV infection. HCMV major capsid protein transcript was detected in deep periodontal pockets of two adult and two localized juvenile periodontitis patients but not in any shallow periodontal sites. The findings suggest that active HCMV replication can occur in periodontal sites. Further studies are necessary to establish whether periodontal reactivation of HCMV correlates with the initiation or progression of destructive periodontal disease.

Adolescent↗
PubMed1998

Risk indicators for harboring periodontal pathogens.

The risk for harboring 6 putative periodontal pathogens in 4 selected periodontal pockets, in whole saliva, or in either site (i.e., orally) was determined in 52 Caucasians, 49 African-Americans, 48 Asian-Americans, and 50 Hispanics living in Los Angeles. 16S rRNA PCR analysis assessed the presence of Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola. Step-wise regression analysis determined the relationship between the occurrence of each organism and various explanatory variables (risk indicators). Periodontal probing depth or disease severity was positively associated with all 6 study organisms. African-Americans carried an increased risk for harboring P. gingivalis in saliva (odds ratio [OR] 2.95) and orally (OR 2.66), and a reduced risk for harboring T. denticola orally (OR 0.34). Asian-Americans showed an increased risk for harboring A. actinomycetemcomitans in periodontal pockets (OR 6.63) and P. gingivalis in periodontal pockets (OR 5.39), in saliva (OR 5.74), and orally (OR 5.81). Hispanics demonstrated an increased risk for harboring A. actinomycetemcomitans in periodontal pockets (OR 12.27) and P. gingivalis in periodontal pockets (OR 6.07), in saliva (OR 8.72), and orally (OR 7.98). Age was positively associated with the prevalence of P. gingivalis in saliva (OR 1.20) and orally (OR 1.20), and of A. actinomycetemcomitans orally (OR 1.18). The male gender was a risk factor for harboring P. intermedia in periodontal pockets (OR 2.40), in saliva (OR 3.31), and orally (OR 4.25), and for harboring P. nigrescens in saliva (OR 2.85). The longer the subjects resided in the United States, the less likely A. actinomycetemcomitans was detected orally (OR 0.82). Former smokers demonstrated a decreased risk for harboring A. actinomycetemcomitans in saliva (OR 0.23). Current smokers displayed an increased risk for harboring T. denticola in periodontal pockets (OR 4.61). The number of dental visits in the past 10 years was inversely related to the prevalence of P. intermedia orally (OR 0.96). The prevalence of P. intermedia in saliva was positively associated with the length of time from the last dental visit (OR 1.01). This study suggests that genetic and/or environmental factors predispose subjects to oral colonization by putative periodontal pathogens.

Adolescent↗
PubMed1998

Clinical and microbiological evaluation of a bioabsorbable and a nonresorbable barrier membrane in the treatment of periodontal intraosseous lesions.

Clinical and microbiological features of periodontal healing in barrier membrane-treated sites were determined in a randomized clinical trial. The study included 10 patients with advanced adult periodontitis and a minimum of one set of similar 2 to 3 wall intraosseous periodontal lesions with no furcation involvement. In each patient, one periodontal lesion was treated with a biodegradable membrane and a contralateral lesion with a nonresorbable barrier membrane. Within the preceding 3 months of regenerative therapy, all patients received full mouth osseous surgery except for the sites for regeneration, were instructed in oral hygiene, and were prescribed systemic ciprofloxacin and metronidazole (250 mg of each, TID, 8 days), starting 7 days before membrane placement. At baseline and at 6 months postsurgery, probing depth and clinical attachment level were assessed in each study site. The subgingival presence of suspected periodontal pathogens was determined by non-selective and selective culture and by DNA probe analyses, and of human cytomegalovirus (HCMV) and Epstein-Barr virus type 1 (EBV-1) by a nested-polymerase chain reaction detection method. At baseline, the barrier-treated sites did not differ significantly in clinical and microbial parameters. Mean baseline probing depth was 7.8+/-1.1 mm for bioabsorbable and 7.9+/-1.3 mm for nonresorbable barrier-treated sites. At 6 months, sites treated with bioabsorbable barrier revealed 4.6+/-1.7 mm gain of clinical attachment (range: 1 to 7 mm) and sites treated with nonresorbable barrier 4.2+/-2.0 mm (range: 1 to 8 mm). The 11 barrier-treated sites that harbored 10% or less bacterial pathogens and were free of HCMV and EBV-1 averaged significantly more clinical attachment gain than the 9 sites that yielded more than 10% bacterial pathogens and/or test viruses (5.6 mm versus 3.0 mm; P=0.005). The present data suggest bioabsorbable and nonresorbable barriers provide similar clinical healing of 2 to 3 wall intraosseous periodontal lesions, emphasize the importance of controlling bacterial pathogens prior to and during periodontal healing, and point to the possible detrimental role of HCMV and EBV-1 in periodontal repair.

Adult↗
PubMed1998

The utility of whole saliva to detect the oral presence of periodontopathic bacteria.

This study compared the presence of 6 periodontopathic bacteria in whole saliva and subgingival plaque of 202 subjects. The test bacteria were identified using a 16S rRNA-based PCR detection method. Each study subject contributed a whole saliva sample and a paper point sample pooled from the deepest periodontal pocket in each quadrant of the dentition. The kappa test revealed a fair agreement between the presence of Porphyromonas gingivalis, Prevotella intermedia, and Treponema denticola in whole saliva and periodontal pocket samples (kappa > 0.4). The McNemar test showed that the differences between sample types were due to a more frequent detection of the 3 organisms in whole saliva than in periodontal pocket samples (P < 0.01). Prevotella nigrescens also was detected more frequently in whole saliva than in periodontal pocket samples (P < 0.01; McNemar test). Although little agreement between samples was found for Actinobacillus actinomycetemcomitans and Bacteroides forsythus (kappa < or = 0.4), neither whole saliva nor pocket samples showed better detection for these 2 species (P < 0.01, McNemar test). The results indicate that whole saliva is superior to pooled periodontal pocket samples to detect P. gingivalis, P. intermedia, P. nigrescens, and T. denticola in the oral cavity. The detection of oral A. actinomycetemcomitans and B. forsythus with reasonably good accuracy may require both whole saliva and periodontal pocket samples.

Adult↗
PubMed1997

[Encapsulated coronary rupture following stent implantation].

We report a case of coronary encapsulated rupture following stent implantation in the distal anastomosis of a saphenous by-pass graft to the left anterior descending coronary artery that evolved well with conservative treatment. The patient did not require pericardiocentesis and was treated with prolonged inflations with low pressure autoperfusion balloon at the rupture point. Pericardial adherences related to a previous coronary surgery probably limited the bleeding process avoiding hemodynamic collapse.

Angioplasty, Balloon, Coronary↗
PubMed1997

Human Herpesviridae in acute necrotizing ulcerative gingivitis in children in Nigeria.

Herpesviruses have been implicated in the pathogenesis of human periodontitis. The present study investigated whether herpesviruses are present in the lesions of acute necrotizing ulcerative gingivitis. Sixty-two Nigerian children, aged 3-14 years, were studied. Twenty-two children had acute necrotizing ulcerative gingivitis and were also malnourished, 20 exhibited no acute necrotizing ulcerative gingivitis but were malnourished and 20 were free of acute necrotizing ulcerative gingivitis and in a good nutritional state. Polymerase chain reaction methods were used to determine the presence of human cytomegalovirus (HCMV), Epstein-Barr virus type 1 and type 2 (EBV-1, EBV-2), herpes simplex virus (HSV), human herpes virus 6 (HHV-6), human papilloma virus and human immunodeficiency virus type 1 in crevicular fluid specimens collected by paper points. Of the 22 acute necrotizing ulcerative gingivitis patients, 15 (68%) revealed viral infection and 8 (36%) viral coinfection. Thirteen (59%) acute necrotizing ulcerative gingivitis patients demonstrated HCMV, 6 (27%) EBV-1, 5 (23%) HSV and 1 (5%) HHV-6. Only 2 (10%) subjects from each group not affected by acute necrotizing ulcerative gingivitis showed viral presence, and no control subject revealed viral coinfection. These findings suggest that HCMV and possibly other herpesviruses contribute to the onset and/or progression of acute necrotizing ulcerative gingivitis in malnourished Nigerian children.

Acute Disease↗
PubMed1997

Evaluation of selected antibiotic residue screening tests for milk from individual goats.

Because somatic cell counts (SCC) of caprine milk are higher than SCC of bovine milk, the performance of antibiotic residue tests for screening bovine milk was investigated for caprine milk. Eighty-five does that were free of antibiotic usage for at least 30 d and that were free of clinical mastitis were sampled at three milkings during a 37-d period. At each sampling, foremilk was collected for bacteriological analysis, and composite bucket milk samples were collected for antibiotic testing and SCC. Day of lactation, parity, 305-d mature equivalent milk yield, and SCC averaged 221 d (57 to 577 d), 2.3 lactations (one to nine lactations), 1160 kg (623 to 1750 kg), and 2.2 x 10(6)/ml (0.3 to 30.7 x 10(6)/ml), respectively. The mean Dairy Herd Improvement Association test day milk yield for the month of sample collection was 3 kg (1.4 to 6.4 kg). Intramammary infections were present in 54% of the goats and in 36% of the udder halves. Assays included positive (5 and 10 ppb of penicillin-G and 50 ppb of ceftiofur) and negative controls that had been prepared in caprine milk and controls supplied by the manufacturers. One false-negative outcome and one false-positive outcome were recorded. For one sampling day, a positive linear relationship existed between SCC and the results of one test, and a quadratic relationship existed between SCC and the results of another test. The antibiotic residue screening tests for milk from individual goats adequately identified milk that was free of antibiotic. These tests are therefore recommended for use with caprine milk.

Animals↗
PubMed1997

Persistence of subclinical intramammary pathogens in goats throughout lactation.

The goal of this study was to determine the persistence of caprine intramammary pathogens throughout lactation and to detect the bias in diagnoses when a single milk sample was used. We studied 131 goats throughout 7 mo of lactation. Goats were sampled monthly, and 1834 milk samples were bacteriologically analyzed. One hundred sixty-eight pathogens were isolated: 82.5% were micrococci, 9.5% were Gram-negative bacilli, and 8% were corynebacteria. An intramammary infection (IMI) was considered a true, persistent IMI when the same pathogen was isolated two or more times consecutively from the same half of the udder. One hundred one samples were considered to be truly positive, which produced persistent IMI caused by nine different species (eight Staphylococcus spp. and one Pseudomonas sp.). Statistical relationships were found between staphylococci and true-positive diagnosis and between corynebacteria and false-positive diagnosis. No relationship involving Gram-negative bacilli was detected. A single milk sample had a positive predictive value (60%), high sensitivity (96.2%), high specificity (96.1%), and highly negative predictive value (99.8%).

Animals↗