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Biomedical subjects

C Wolff

Publications and source records attributed to C Wolff.

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

Fast preattentive processing of location: a functional basis for selective listening in humans.

Spatial separation of sound sources provides a primary cue for selecting relevant from irrelevant acoustic input. This competence for selective listening is important in every-day life, when several concurrent sound sources are simultaneously active. The present study demonstrated a temporal advantage in the preattentive processing of location information relative to frequency information. This was indicated by shorter latency of the mismatch negativity (MMN), generated by the brain's automatic detection of a sound change, to a location change than to a frequency change. Results suggest that the superior role of spatial location for selective listening may be due to faster automatic encoding of spatial information into the neural representations underlying attentional selection.

Adult↗
PubMed1997

Anti-arthritic activity of hydroxamic acid-based pseudopeptide inhibitors of matrix metalloproteinases and TNF alpha processing.

OBJECTIVE AND DESIGN: The effects of two hydroxamate inhibitors of metalloproteinase and tumor necrosis factor alpha (TNF alpha) processing on endotoxin-induced plasma TNF alpha and arthritic lesions in adjuvant-induced arthritic (AA) rats were determined. MATERIAL AND TREATMENT: BB-1101 and BB-1433 were administered orally twice daily to AA Lewis rats with an established disease (days 13 to 22). AA rats (day 16) or normal rats were injected with bacterial endotoxin and plasma levels of TNF alpha were also determined. METHODS: Hindpaw swelling was measured plethysmographically. Bone degradation was determined by radiography and bone mineral densitometry. TNF alpha was quantified using a sandwich ELISA. RESULTS: The hydroxamic-acid pseudopeptides inhibited plasma. TNF alpha levels in vivo and significantly reduced swelling and bone degradation of the tibiotarsal joints of AA rats in the range of 10-50 mg/kg given orally (p < 0.01 by Student's t-test). CONCLUSIONS: Thus, these novel compounds offer a new disease modifying therapy for arthritis and the results also suggest that inhibition of TNF alpha production may contribute, at least in part, to their anti-arthritic activity.

Animals↗
PubMed1997

[Results of elastic plate osteosynthesis of simple femoral shaft fractures in polytraumatized patients. An alternative procedure].

Primary medullary nailing of femoral fractures is burdened by the risk of central and pulmonary complications in patients with polytrauma, especially in conjunction with craniocerebral or thoracic trauma. This also applies to unreamed medullary nailing. Primary treatment with external fixation necessitates secondary surgery with an altered procedure, the timing of which is not predictable. Plate osteosynthesis with anatomical repositioning of the fragments and rigid fixation is a technically demanding procedure, but can lead to fragment necrosis due to fragment denudation. In a prospective study conducted from 1 September 1994 to 30 June 1996 on 17 polytraumatized patients (average ISS:30 points), simple femoral stem fractures (A-1 to B-3 of the AO-classification) were stabilized by elastic plate osteosynthesis using biological technique. While cautiously preserving the periosteal and muscle connections to the bone, a plate is inserted as a bridge without any interfragmentary compression. At least two to four holes are left free in the center of the plate. This allows micro-movements in the fracture gap without the risk of material fatigue. All of the fractures were immediately stabilized on the day of the accident. In four patients with severe craniocerebral trauma or manifest shock, the procedure was changed to plate osteosynthesis after application of primary external fixation. Secondary injuries (joint and pelvic fractures or craniocerebral trauma) delayed early loading in 12 cases. Four patients were mobilized postoperatively under partial loading. A fixation callus was radiologically detectable on average 6 weeks after surgery. This often allowed additional loading, depending on the secondary injuries. Full loading was possible after 14 weeks. Complications included one case of surgery-related malpositioning, one soft-tissue infection, one case of plate detachment after a fall and one case of periosseous calcification. There were no cases of bone infections or pseudoarthroses. Elastic plate osteosynthesis is thus a conservative osteosynthesis procedure with a low complication rate in polytraumatized patients, even in those with simple femoral fractures.

Adolescent↗
PubMed1997

Interaction with a lipid membrane: a key step in bacterial toxins virulence.

Bacterial toxins are secreted as soluble proteins. However, they have to interact with a cell lipid membrane either to permeabilize the cells (pore forming toxins) or to enter into the cytosol to express their enzymatic activity (translocation toxins). The aim of this review is to suggest that the strategies developed by toxins to insert in a lipid membrane is mediated by their structure. Two categories, which contains both pore forming and translocation toxins, are emerging: alpha helical proteins containing hydrophobic domains and beta sheets proteins in which no hydrophobicity can be clearly detected. The first category would rather interact with the membrane through multi-spanning helical domains whereas the second category would form a beta barrel in the membrane.

Amino Acid Sequence↗
PubMed1997

Association of Ureaplasma urealyticum biovars with clinical outcome for neonates, obstetric patients, and gynecological patients with pelvic inflammatory disease.

In this prospective study, the prevalence of the two Ureaplasma urealyticum biovars, parvo and T960, was determined in pregnant women and in gynecological patients colonized by ureaplasmas. Furthermore, we investigated the association of these biovars with gynecological complications and adverse pregnancy outcome. Isolates of U. urealyticum from 254 women were biotyped by a PCR method recently developed. The parvo biovar was found in 81% (206 of 254) of the patients, and the T960 biovar was found in 30% (76 of 254) of the patients; 6% (14 of 254) of the women were coinfected. Identical biovars were detected in mothers and their infants. Serial isolations or cultures from different sampling sites of the same individual revealed the same biovar. T960 was dominant in patients with pelvic inflammatory disease (57%) and patients who had had a miscarriage (42%), showed a higher rate of tetracycline resistance than did parvo isolates (55 versus 18%), and seemed to have more adverse effects on pregnancy outcome with regard to birth weight (2,500 versus 1,720 g), gestational age (35 versus 30 weeks), and preterm delivery (35 versus 77%).

Female↗
PubMed1997

[Porphyrin excretion in patients with chronic hepatitis C virus infection].

BACKGROUND: The high prevalence of chronic hepatitis C virus infection in patients with porphyria cutanea tarda, specially in those without family history of the disease, suggests that this could be an acquired disease and one of the most frequent extra hepatic manifestations of hepatitis C virus infection. AIM: To study the excretion of porphyrins and its precursors in cirrhotic patients with and without hepatitis C virus infection. PATIENTS AND METHODS: Eighteen patients with cirrhosis Child-Pough A, eight infected with hepatitis C virus, were studied. Urinary excretion of [symbol see text] aminolevulinic acid, porphobilinogen, coproporphyrins, uroporphyrins and fecal excretion of coproporphyrins and protoporphyrins were measured. Red blood cell protoporphyrin was also measured. RESULTS: There were no differences in the measured parameters between patients with or without hepatitis C virus infection. No patient had uroporphyrin excretion values over the normal range. Some patients had slight elevations in some parameters, but always below the values observed in porphyrias. CONCLUSIONS: In these group of patients, hepatitis C virus infection of its associated liver disease, do not cause detectable alterations in porphyrin metabolism.

Adult↗
PubMed1996

Mismatch response of the human brain to changes in sound location.

WE investigated whether the enhanced negativity of the human event-related brain potential elicited by changes in auditory lateralization is due to a higher-order change-detection process or whether it can be explained exclusively in terms of selective sensory adaptation. Infrequent changes in lateralization of a repetitive standard tone, generated by changes in interaural time differences, elicited a frontocentrally distributed negative brain wave in the 100-250 ms range relative to stimulus onset. This brain wave was also elicited when possible sensory adaptation was prevented by controlling for the state of refractoriness of location-specific neurones. The results demonstrate that changes in lateralization elicit a genuine mismatch negativity (MMN), indicating the activity of an automatic higher-order change-detection process.

Adult↗
PubMed1996

Significance of human cytomegalovirus DNA detection in immunocompromised heart transplant patients.

Peripheral blood samples (n= 1240), obtained at variable intervals from 483 heart transplantation (HTx patients under immunosuppressive therapy, and blood samples (n=1013) obtained upon blood donation from 1013 healthy anti-human cytomegalovirus (HCMV) positive blood donors, were tested for HCMV DNA by nested polymerase chain reaction (PCR). The detection limit of the nested PCR was determined to be less than 10 copies of the plasmid pRR 47, containing the HCMV immediate early gene. HCMV DNA was detected in 79 of 483 HTx patient (17%). To the contrary' HCMV DNA was only detected in 1 of 1013 anti-HCMV positive, healthy blood donors (0.1%). This PCR positive donor had recently contracted a primary HCMV infection. The rate of HCMV PCR positive immunosuppressed HTx patients in our study was lower than the rate of HCMV PCR positive healthy blood donors in previous reports in the literature. Blood samples (269 from 117 HTx patients) were assayed for HCMV DNA in peripheral blood leukocytes, HCMV DNA in plasma, and HCMV tegument protein 65 kDa (pp 65 antigen). Three laboratory diagnostic patterns were observed and related to clinical findings: (1) HCMV DNA only in leukocytes was observed in 26 patients, 7 of whom had HCMV disease, 5 of whom had graft rejection, and 14 of whom had no specific symptoms; (2) HCMV DNA both in leukocytes and in plasma (viremia) was observed in 3 patients, who were all symptomatic with HCMV disease; (3) HCMV DNA in leukocytes and in plasma (viremia) and pp 65 antigen were observed in 13 patients, all of whom were symptomatic (10 patients had HCMV disease, and 3 patients had graft rejection). A similar sequence of diagnostic patterns was observed in all symptomatic HCMV infections and reactivations in this study: HCMV DNA appeared first in peripheral blood leukocytes, then also in plasma, followed by pp 65 antigen detectable in peripheral blood leukocytes. Upon clinical recovery, these findings disappeared in reverse order. However, HCMV DNA remained detectable in peripheral blood leukocytes for several weeks. The detection of HCMV DNA in the peripheral blood is an exception, not the rule, even in severely immunosuppressed HTx patients. It indicates a pathological condition, albeit without clinical symptoms in some patients, and it is the earliest signal of HCMV replication. Of 42 patients in whom HCMV DNA was initially detected only in peripheral blood leukocytes, 16 patients progressed into viremia. Thus, HCMV-specific PCR performed on nucleic acid extracts from lysed peripheral blood is an appropriate method for the monitoring of HCMV infections in immunosuppressed HTx patients.

Antibodies, Viral↗
PubMed1996

Polymerase chain reaction versus culture for detection of Ureaplasma urealyticum and Mycoplasma hominis in the urogenital tract of adults and the respiratory tract of newborns.

The efficiency of the polymerase chain reaction (PCR) was compared with that of culture for detection of Ureaplasma urealyticum and Mycoplasma hominis in 726 clinical specimens comprising 189 gynecological samples, 362 urological samples, and 175 samples from newborn infants. The sensitivity of PCR versus culture was 95% for both organisms, while the sensitivity of culture versus PCR was 91% for Ureaplasma urealyticum and 84% for Mycoplasma hominis. Furthermore, PCR tests were faster than culture tests, allowing the time to diagnosis to be reduced from two to five days to 24 h.

Adult↗
PubMed1996

One of the lowest validated incidence rates of insulin dependent diabetes mellitus in the Americas: Santiago, Chile.

The goal of this study was to estimate the average annual incidence rate of insulin-dependent diabetes mellitus (IDDM) in Santiago as part of a Multinational Project in Childhood Diabetes (Diabetes Mondiale or DiaMond). Incidence was calculated among subjects under 15 years of age, through a retrospective search and confirmation method from 1 January 1986 to 31 December 1992. Hospitals and private offices of endocrinologists and specialists in diabetes were surveyed. A total of 252 registered cases, 118 boys and 134 girls, for an annual incidences of 2.36/100,000 hab.year. which is one of the lowest validated rates in the Americas.

Adolescent↗
PubMed1996

Longitudinal monitoring of latent and active human cytomegalovirus infections in peripheral blood of heart transplant recipients by single-tube nested RT-PCR.

PCR is a sensitive diagnostic tool for the detection of human cytomegalovirus (HCMV) DNA in the peripheral blood of immunosuppressed transplant recipients. However, its specificity as a prognostic marker for clinical disease is unclassified, because infections considered to be latent may be detected by this method. In order to diagnose active viral infections, we used reverse transcription-PCR (RT-PCR) to identify HCMV mRNA in blood. We developed a single-tube nested RT-PCR with preformed PCR mixtures embedded in a trehalose matrix. Blood samples of 48 heart transplant recipients were investigated for HCMV DNA. 8 patients detected to be HCMV DNA positive after transplantation were investigated in longitudinal monitoring for at least 6 months. HCMV mRNA was found in 5 patients who developed HCMV related symptoms during the period of RNA detection. There was no clear relation between the onset of DNA detection and the first demonstration of mRNA. In 2 patients HCMV DNA could be detected 74 and 81 days before the appearance of mRNA, suggesting long persistence until active infection is started. In 3 patients HCMV mRNA disappeared during or immediately after the end of ganciclovir therapy. In contrast, HCMV DNA was detectable continuously for prolonged periods after therapy, indicating that the persistence of HCMV DNA is not influenced by ganciclovir treatment. In summary, HCMV DNA detection seems to be a reliable early marker for the differentiation of persistent and active HCMV infections in immunosuppressed patients. Our data show that viral mRNA detection is probably a better predictor of the effectiveness of antiviral therapy than viral DNA detection.

Antibodies, Viral↗
PubMed1996

Preattentive periodicity detection in auditory patterns as governed by time and intensity information.

The present study demonstrated that the mismatch negativity (MMN), generated by the brain's preattentive detection of a sound change, is elicited by infrequent reversals of two consecutive tones differing in intensity. When tones were presented in a pairwise manner, the MMN was time-locked to the onset of the intensity reversal. When the tones were continuously presented, the MMN was elicited by an irregular loud tone succeeding a regular loud tone but not by an irregular soft tone following a regular soft tone. Results suggest that the preattentive construction of auditory units is primarily governed by the timing of tone presentation but that it may also utilize intensity information, when no sufficient timing information is available.

Acoustic Stimulation↗
PubMed1996

[Incidence of insulin-dependent diabetes mellitus in Santiago, Chile (1990-1993)].

The aim of this study was to determine IDDM incidence in the Metropolitan Region of Chile, during the period 1990-1993 as part of the Multinational Project for Childhood Diabetes (WHO DIAMOND Project Group). The studied population was 1499.784 inhabitants. All children in whom the diagnosis was made between January 1, 1990 and December 31, 1993 were included. We used a retrospective and prospective search and confirmation method, using as data sources public and private hospitals and medical records of Pediatricians. The Juvenile Diabetes Foundation was used as a secondary data source. All cases had at least two confirmation sources. A total of 176 new cases (90 male) were diagnosed in the study period, with an annual incidence of 2.92/100,000 for females and 2.95 for males. The group of children from 10 to 14 years old had the highest incidence rate (4.9/100,000), specially in women (5.25/100,000). The yearly incidence was 1.31 in 1990, 2.71 in 1991, 2.93 in 1992 and 3.7/1000,000 in 1993. It is concluded that the Metropolitan Region has one of the lowest incidences of IDDM in Latin America, although it increased along the study years.

Adolescent↗
PubMed1996

[Treatment of porphyria cutanea tarda with chloroquine and its effect on associated liver disease: retrospective analysis].

BACKGROUND: Chloroquine may improve cutaneous symptoms and liver disease manifestations in patients with porphyria cutanea tarda. AIM: To retrospectively analyze the effects of choloroquine in patients with porphyria cutanea tarda. PATIENTS AND METHODS: Five patients (one female), aged 45 to 65 years old, were studied. The duration of the disease ranged from 2 to 15 years. One patient was alcoholic and other was a hepatitis C virus carrier. All patients received chloroquine 125 mg twice weekly. Before, during and after treatment, cutaneous signs, serum bilirubin, hepatic enzymes and urine copro and uroporphyrin were assessed. Four patients were subjected to a liver biopsy before starting chloroquine. RESULTS: All patients had increased levels of urine porphyrins, four had abnormal serum liver enzymes. All liver biopsies showed variable hemosiderosis, two patients had a chronic active hepatitis (one with cirrhosis), one a chronic persistent hepatitis and one had mild rague alterations. During chloroquine treatment, cutaneous symptoms improved in all patients, transaminases and gamma glutamyl transferase decreased. In three, urine uroporphyrin increased initially and normalized afterwards. Choloroquine was well tolerated. CONCLUSIONS: Chloroquine improved cutaneous symptoms, urine uroporphyrin and serum liver enzyme levels in treated patients.

Aged↗