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Biomedical subjects

A Gonzalez

Publications and source records attributed to A Gonzalez.

At least 145 records · Page 8Linked to original sources
PubMed1996

Idiopathic orbital inflammation with intracranial extension. Case report.

Idiopathic orbital inflammation or orbital pseudotumor with intracranial extension is a rare condition. It consists of a nonspecific infiltrate of the fatty tissue of the orbit that extends through one or more foramina into the adjacent intracranial tissue. The lesion mimics an infectious or neoplastic lesion. The authors present a case involving the youngest patient yet reported with the broadest intracranial extension. Only 17 previous cases have been reported. The principal symptoms include decreased visual acuity and proptosis. Extension commonly develops through the superior orbital fissure into the middle cranial fossa and the cavernous sinus. The initial treatment is a regimen of high-dose steroids, with radiotherapy given in unresponsive cases.

Adolescent↗
PubMed1996

Tinnitus and Post-Traumatic Vertigo - A Review.

Fifteen neuro-otological patients have been investigated for post-traumatic vertigo, hearing loss and tinnitus. Clinical examination and laboratory tests included audiometry and equilibriometry in all patients. Statistically significant findings are reported for tinnitus, vertigo, hearing loss. Correlations for vertigo with the type of head trauma, nystagmus frequency Slow Phase Velocity (SPV) and associated complaints of hearing loss and tinnitus were analyzed. The most frequent symptom reported was vertigo (73.3%); lift sensation (46.6%); tilting and falling (26.6%); and tinnitus (40%).

Journal Article↗
PubMed1996

Morphological classification of facial features in adult Caucasian males based on an assessment of photographs of 50 subjects.

Fifty sets of photographs showing facial features of Caucasian males aged 18 to 60 years were examined to establish a morphological classification of the face. It is suggested that such a classification could assist facial identification by photocomparison. The selection criteria stress the importance of interassessor agreement and discrimination among feature subset units in formulating the proposed classification.

Adolescent↗
PubMed1996

Pediatric experience with autologous peripheral blood progenitor cell transplantation: influence of CD34+ cell dose in engraftment kinetics.

The aim of this study was to analyze factors affecting mobilization and engraftment in 40 children undergoing autologous peripheral blood progenitor cell transplantation for different malignancies: 19 patients with haematological malignancies and 21 patients with solid tumors. Patients received 4-5 days of rhG-CSF (12 micrograms/kg/day) subcutaneously. Apheresis was performed by continuous flow blood cell separation beginning on the fifth day of rhG-CSF. For patients weighing < or = 25 kg, the extracorporeal line was primed with irradiated red blood cells. After myeloablative conditioning regimens, patients were grafted with 7.21 +/- 7.8 x 10(6)/kg CD34+ cells. Days to achieve an absolute neutrophil count > 0.5 x 10(9)/1 and a platelet count > 20 x 10(9)/1 without platelet support were 9.50 +/- 1.2 (range 7-13) and 18.1 +/- 8.3 (range 9-37), respectively. The number of CD34+ cells infused was highly correlated with engraftment kinetics (P = 0.0001). The patient's body weight and the number of previous chemotherapy courses had a negative influence on CD34+ cells collected.

Adolescent↗
PubMed1995

Pf1 filamentous bacteriophage: refinement of a molecular model by simulated annealing using 3.3 A resolution X-ray fibre diffraction data.

The filamentous bacteriophage Pf1 is structurally similar to the well known Ff (fd, fl, M13) strains, but it gives much better X-ray diffraction patterns, enabling a more detailed analysis of the molecular structure. The 46-residue protein subunit can be closely approximated by a single gently curved stretch of alpha-helix. The axes of the subunits are at a small angle to the virion axis, and several thousand subunits form an overlapping inter-digitated helical array surrounding a DNA core. We have derived a detailed model of the virion based on X-ray data and stereochemical constraints. We have considered potential sources of error in the diffraction data, and used the improved data to study regions where the protein subunit of Pf1 may deviate from a continuous alpha-helix. We use simulated annealing to escape from local minima, and various kinds of electron-density maps to guide the model building. Refinement of the model shows that the first few residues at the N terminus are non-helical, and there is a slight discontinuity in the alpha-helix near the middle of the sequence. The model is consistent both with general structural principles derived from high-resolution analysis of other proteins, and with specific chemical and spectroscopic data about Pf1. We apply the same refinement techniques to an alternative model with a non-helical surface loop between residues 13 and 19. Comparative analysis of models with and without a loop shows that the loop model is not supported by 3.3 A resolution X-ray diffraction data.

Journal Article↗
PubMed1995

Thoracic spinal nerve and root conduction: a magnetic stimulation study.

We describe a technique of magnetic coil (MC) stimulation of the thoracic spinal nerves and roots in 12 normal subjects and a patient with diabetes mellitus. We kept the MC flat against the vertebral column in the midline over T-7, T-8, and T-9 spinous processes and obtained compound muscle action potentials from the upper rectus abdominis, external oblique, and intercostal muscles. We obtained mean latencies to these muscles after stimulation in the posterior axillary line. We noted that the onset latencies remained fixed despite increasing the intensity of stimulation from 30% to 100% and on moving the coil up to 3 cm lateral to the spinous processes suggesting that the stimulation of the fastest conducting fibers was occurring at a fixed site, most likely at the intervertebral foramina. Prolonged latencies in the diabetic patient confirmed the diagnosis of radiculoneuropathy.

Adult↗
PubMed1995

Mechanisms for episodes of hypoxemia in preterm infants undergoing mechanical ventilation.

OBJECTIVE: To ascertain possible mechanisms implicated in the development of transient episodes of hypoxemia (oxygen saturation < 85%) frequently observed in preterm infants undergoing mechanical ventilation, even after the acute phase of respiratory failure has passed. STUDY DESIGN: Tidal flow, airway and esophageal pressure, and oxygen saturation were continuously recorded in 10 infants (mean +/- SD, birth weight 733 +/- 149 gm, gestational age 25.5 +/- 2.2 weeks, age 26.3 +/- 11.9 days) who had repeated episodes of hypoxemia without any evident cause. Measurements of minute ventilation (VE) inspiratory compliance (Ci), and inspiratory resistance (Ri) were compared before and during episodes of hypoxemia. RESULTS: All episodes of hypoxemia were preceded by an active exhalation that produced a mean decrease in end-expiratory lung volume of 6.4 +/- 2.8 ml/kg. The reduction in lung volume was immediately followed by a sudden decrease in tidal flow and volume, despite continuation of mechanical ventilation at the same rate and peak pressure. The resulting hypoventilation was associated with a drop in Ci to approximately one half and an increase in Ri to more than double the baseline values. Approximately 30 seconds after the beginning of hypoventilation, the arterial oxygen saturation reached a hypoxemic level (oxygen saturation < 85%)> CONCLUSION: Most hypoxemic episodes were triggered by an expiratory effort that produced a large decrease in lung volume. This reduction in lung volume probably leads to closure of small airways and the development of intrapulmonary shunts, which would explain the rapid development of hypoxemia.

Analysis of Variance↗
PubMed1995

Changing trends in the epidemiology and pathogenesis of neonatal chronic lung disease.

OBJECTIVE: To assess the role of specific risk factors that may predispose preterm infants with mild or no initial respiratory distress syndrome to the development of chronic lung disease (CLD). STUDY DESIGN: Clinical data were collected prospectively from 119 ventilator-supported preterm infants with birth weights between 500 and 1000 gm, who survived more than 28 days and required fewer than 3 days of treatment with fraction of inspired oxygen > 25% during the first 5 days of life. Logistic regression analysis was used in a multivariate assessment of risk factors for CLD. RESULTS: Chronic lung disease occurred in 44 of the patients (37%). The analysis showed that low birth weight, patent ductus arteriosus (PDA), and sepsis were significant risk factors for CLD. The corresponding odds ratios for CLD and their 95% confidence intervals (CI) were as follows: 2.9 per 100 gm birth weight decrement (CI, 1.7 to 4.8); 6.2 (CI, 2.1 to 18.4) for PDA; and 4.4 (CI, 1.3 to 14.5) for sepsis. When sepsis and PDA occurred simultaneously, the odds ratio for CLD increased to 48.3 (CI, 6.3 to > 100) in comparison with infants without these conditions. Episodes of PDA were categorized as either early (occurring during the first week of life) or late (after the first week), and the respective odds ratios for CLD were 2.8 (CI, 0.8 to 9.4) and 21.1 (CI, 5.6 to 80) in comparison with infants without PDA. For the duration of symptomatic PDA, the odds ratio for CLD was 3.5 per week that the PDA remained open (CI, 1.9 to 6.5). CONCLUSION: CLD is a frequent sequela in very low birth weight infants with mild or no respiratory distress syndrome. In this population, the development of late episodes of PDA, usually in association with a nosocomial infection, seems to play a primary role in the pathogenesis of CLD.

Chronic Disease↗
PubMed1995

Prediction of recurrence in B-C stages of colorectal cancer by p53 nuclear overexpression in comparison with standard pathological features.

This study investigated the predictive value of p53 nuclear overexpression on recurrence of colorectal adenocarcinomas compared with established prognostic pathological features. Sixty-one paraffin-embedded sections from primary tumours were examined by immunohistochemistry. Specific nuclear staining was detected in 27 (44.2%) cases. Positivity was more frequent in tumours with venous invasion (76.9%) (P = 0.06) and in rectal cancer (68.4%) (P = 0.06). After a median observation time of 46 months, p53-positive tumours exhibited a higher percentage of recurrence (40.7% vs 11.7%) (P = 0.03), and a higher likelihood of relapse at 5-year follow-up (46% vs 13%) (P = 0.006). Among the pathological variables analysed, only the extent of bowel wall invasion showed a relationship with recurrence. After adjustment for the other covariates in a Cox's regression model, p53 overexpression was the only factor showing independent prognostic significance (hazard ratio: 4.96; 95% Confidence Interval (CI): 1.47-16.71) (P = 0.012). The results of this study show that nuclear p53 protein overexpression has higher predictive value than standard pathological variables.

Adenocarcinoma↗
PubMed1995

Long interval between HCV infection and development of hepatocellular carcinoma.

A high prevalence of HCV infection has been reported in patients with hepatocellular carcinoma. The progression from acute transfusion-associated hepatitis to hepatic cirrhosis and hepatocellular carcinoma has been suggested in several studies to be very long. We have investigated the prevalence of anti-HCV and the interval between HCV infection and hepatocellular carcinoma among 191 consecutive patients with cirrhosis and liver-cell carcinoma. Serum samples from 191 patients with cirrhosis and hepatocellular carcinoma, consecutively diagnosed in our hospital between 1988 and 1993, were tested for serological markers of HBV and HCV infection. One hundred and forty-eight patients (77.5%; 95% confidence interval (c.i): 76% to 80%) were anti-HCV positive by 2nd generation enzyme immunoassay (confirmed by 2nd generation recombinant immunoblot assay) and 152 patients (79.5%; 95% c.i: 76% to 80%) were anti-HCV positive by 3rd generation enzyme immunoassay, while only 14 (7.4%; 95% c.i: 5% to 10%) were HBsAg positive. Of the 29 anti-HCV positive patients with previous transfusion, the interval between the date of blood transfusion and the diagnosis of hepatic cirrhosis was 24 +/- 12.5 years and that of hepatocellular carcinoma was 26.8 +/- 12.4 years. These results confirm the high prevalence of HCV infection in patients with hepatocellular carcinoma and the slow sequential progression from HCV infection through cirrhosis and hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed1995

Reclosure of the open abdomen.

BACKGROUND: The open abdomen technique for the treatment of diffuse peritonitis has gained acceptance. Our approach has been to use the zipper technique with daily irrigations. Once the abdominal problem has resolved, the mesh and zipper are removed. Surgeons are reluctant to reoperate on patients with such prior treatment because of the anticipation of a hostile abdomen. Our study is a retrospective review of 12 patients who were treated with the open abdomen technique. At a later date, they underwent elective reoperation. STUDY DESIGN: The charts of 12 patients were reviewed. After initial injury, the patients were in the surgical intensive care unit. Reoperations were performed nine months (mean) after discharge from this facility. The reasons for reoperation were closure of enteric fistula (five patients) and closure of an ostomy (seven patients). The abdominal wall was reconstructed in nine patients. In the other three patients, the abdomen was entered through a lateral incision and the bowel was reanastomosed. RESULTS: All of the patients survived. There were five complications. Two patients had ischemic skin grafts successfully treated by hyperbaric oxygen therapy (HBO). Two patients had ischemic skin flaps that were covering mesh. They responded to HBO with minimal slough of superficial tissue. One patient had a low output fistula that closed after two weeks of total parenteral nutrition. CONCLUSIONS: A history of an open abdomen is not a contraindication to later operation. Bowel continuity can be restored and abdominal wall reconstruction can be performed safely. This can be done as early as three to four months after recovery from the original injury.

Abdomen, Acute↗
PubMed1994

Radiation damage in protein crystals at low temperature.

This paper describes the study of the effects of radiation damage on the quality of data collected from a protein crystal at 100 K. It is shown that radiation damage causes measurable effects in the diffraction pattern. This implies that, even at liquid nitrogen temperatures, there is a limit to the size of a crystal from which a complete data set can be collected.

Journal Article↗
PubMed1994

Data collection at short wavelengths in protein crystallography.

The development of high-intensity X-ray sources and the use of insertion devices will make it possible to collect data routinely from protein crystals at very short wavelengths (lambda </= 0.5 A). Possible benefits of using shorter wavelengths can be inferred from the improvement in the quality of the data when using a wavelength lambda approximately 0.9 A instead of one close to the Cu Kalpha emission edge. In addition to fewer absorption errors, two factors might contribute to this improvement. These are an increase in the lifetime of the protein crystal and a better signal-to-background ratio. In this paper we address the second of these. In order to compare the quality of the data and the relative background level in the diffraction patterns at different wavelengths two data sets have been collected at lambda = 0.92 and 0.55 A. The results obtained from data processing and careful measurement of the background in the raw images suggest that, in the absence of absorption errors and radiation damage, data collection at very short wavelengths does not provide higher quality data. There is no improvement in the signal-to-background ratio in the short-wavelength data.

Journal Article↗
PubMed1994

Anti-LFA-1 (CD11a) monoclonal antibody interferes with neonatal induction of tolerance to alloantigens.

The injection of (C57BL/6 x BALB/c)F1 spleen cells into newborn BALB/c mice results in the induction of a specific cytotoxic T lymphocyte (CTL) tolerance to the alloantigens. On the contrary, alloreactive CD4+ T cells persist in the host and are still able to activate autoreactive F1 B cells to produce autoantibodies. This state of "split tolerance" is closely associated with the development of a lupus-like autoimmune syndrome. The LFA-1 integrin plays a relevant role in homing, intercellular adhesion and tranduction of co-stimulatory signals in leukocytes. Because of the beneficial effects of anti-LFA-1 monoclonal antibodies (mAb) treatment in various models of organ transplantation and autoimmune disease, we have investigated if such a treatment could interfere with the induction of neonatal tolerance or the development of the autoimmune syndrome in F1 cell-injected newborn mice. For this purpose, BALB/c mice neonatally injected with F1 cells were treated from day 1 up to day 15 with a non-cytotoxic anti-LFA-1 (CD11a) mAb. Anti-LFA-1 mAb treatment interfered with the persistence of a stable chimerism and with the establishment of CTL tolerance, as shown by rejection of allogeneic skin grafts and F1 B cells, and by a normal in vitro CTL activity against the corresponding alloantigens. As a consequence, these mice did not develop the characteristic autoimmune features seen in close association with an effective induction of CTL tolerance to alloantigens. These results stress the importance of the interactions between LFA-1 and its ligands during the neonatal induction of tolerance to alloantigens.

Animals↗