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Biomedical subjects

J Isaacson

Publications and source records attributed to J Isaacson.

17 recordsLinked to original sources
PubMed2000

Correlation between human immunodeficiency virus genotypic resistance and virologic response in patients receiving nelfinavir monotherapy or nelfinavir with lamivudine and zidovudine.

The relationship between detectable human immunodeficiency virus (HIV) genotypic resistance and virologic response was compared in patients receiving nelfinavir as monotherapy (16 weeks) or in combination with lamuvidine and zidovudine (48 weeks). Two patient groups were defined on the basis of the presence or absence of substitutions associated with nelfinavir, a protease (PR) inhibitor, and/or a reverse transcriptase (RT) inhibitor. HIV RNA levels <50 copies/mL were achieved in 17 (85%) of 20 combination-therapy patients without genotypic resistance (PR-RT(-)) versus only 1 (17%) of 6 patients with genotypic resistance (PR-RT(+)). PR-RT(-) patients exhibited greater and more durable virus suppression compared with PR-RT(+) patients. All 6 PR-RT(+) patients had virus with M184V (lamuvidine resistance); 3 isolates also contained D30N (nelfinavir resistance). M184V preceded D30N in all determinable instances. In this study, suppression of HIV replication to <50 copies/mL was associated with durable response and reduced incidence of resistance. Results also indicate that combination regimens can fail despite the absence of detectable genotypic PR resistance.

Anti-HIV Agents↗
PubMed2000

Effects of pressure support ventilation and continuous positive airway pressure on diaphragm performance.

Many patients who are on mechanical ventilation are on ventilator modes called pressure support ventilation (PSV) and continuous positive airway pressure (CPAP) particularly when they are being weaned. As the diaphragm is responsible for approximately 75% of breathing, it is important to promote diaphragm shortening to optimize weaning from mechanical ventilation. The purpose of our 1998 quasi-experimental study was to explore the effects of PSV and CPVP on diaphragm shortening. An animal model was utilized using four Sprague-Dawley rats from the same litter purchased from Sasco (Kansas City, USA). Also measured in this study were intrathoracic pressure (DeltaITP), positive inspiratory pressure, respiratory rate, tidal volume, end-tidal carbon dioxide, central venous pressure (CVP) and mean arterial pressure (MAP). Pressure support was increased in increments of 5 cm H2O at CPAP levels of 0, 2 and 4 cm H2O. A direct assessment of diaphragm shortening was achieved through the adherence of a miniaturized ultrasonic sensor to the inferior surface of the middle costal surface of the right hemidiaphragm of four Sprague-Dawley rats. Limitations of this study included a small sample size, anaesthetized rats and abdominal dissection for insertion of the ultrasonic sensor. As PSV was increased, there was a decrease in MAP, CVP, respiratory rate and end-tidal CO2. When increasing levels of CPAP were added to PSV, a decrease in diaphragm shortening was observed. These results support that higher levels CPAP may hinder diaphragmatic function thus prolong mechanical ventilation. The purpose of this pilot study was to explore the effects of PSV and CPAP on diaphragm shortening. Also measured were DeltaITP, positive inspiratory pressure, respiratory rate, tidal volume, end-tidal carbon dioxide, CVP and MAP. Pressure support was increased in increments of 5 cm H2O at CPAP levels of 0, 2 and 4 cm H2O. A direct assessment of diaphragm shortening was achieved through the adherence of a miniaturized ultrasonic sensor to the inferior surface of the middle costal surface of the right hemidiaphragm of four Sprague-Dawley rats. Limitations of this study included a small sample size, anaesthetized rats and abdominal dissection for insertion of the ultrasonic sensor. As PSV was increased, there was a decrease in MAP, CVP, respiratory rate and end-tidal CO2. When increasing levels of CPAP were added to PSV, a decrease in diaphragm shortening was observed.

Animals↗
PubMed1999

Current treatment practices for early laryngeal carcinoma.

OBJECTIVE: Controversy regarding the management of early laryngeal carcinoma persists in the absence of a definitive comparison of treatment modalities. This study examines the basic management practices for early laryngeal cancer among the American Academy of Otolaryngology-Head and Neck Surgery membership with an emphasis on the role of conservation surgery. METHODS: Questionnaires were randomly distributed to 3000 members with 1000 responses. The results were collated and statistically evaluated with multivariable frequency analysis. RESULTS: For operable supraglottic tumors, supraglottic laryngectomy was advocated by 41.6% of those responding. Definitive radiation therapy was suggested by 5.3% of participants and total laryngectomy by 1.4%. Explanation of treatment options with the patient deciding the therapy was selected by 48.3% of responders. For suitable glottic tumors, hemilaryngectomy was recommended by 37.1%, definitive radiation therapy by 8.1%, total laryngectomy by 1.9%, and patient choice by 50.4% of members completing the survey. When patients were left to weigh the treatment options, surgery was much less likely to be chosen than if it was advocated by the physician. Trends were evident according to practice region and setting, but these variables did not correlate strongly with physician recommendations. However, date of residency completion and rating of available radiation oncology services were significant factors. The evaluation of postoperative considerations in laryngeal conservation surgery demonstrated large variability in the definition of a close margin and the perceived need for additional therapy. CONCLUSIONS: The varied practice patterns among the American Academy of Otolaryngology-Head and Neck Surgery membership reflect the lack of a comparative outcome analysis for the treatment of early laryngeal carcinoma. Consequently, the full reliance on patient choice, which is more pronounced among young physicians, and cost considerations may have the greatest impact on the future treatment of this disease.

Glottis↗
PubMed1993

In vitro detection of bovine immunodeficiency-like virus using monoclonal antibodies generated to a recombinant gag fusion protein.

An Escherichia coli recombinant fusion protein containing the major core protein of bovine immunodeficiency-like virus (BIV) was used to immunize mice for generation of monoclonal antibodies to BIV p26. Eight hybridomas specific for BIV p26 were identified and two antibodies, designated 104 and 142, were further characterized. Both 104 and 142 antibodies were isotyped as IgG1; they reacted specifically with both BIV p26 and the recombinant fusion protein in Western immunoblot analyses. However, the epitope specificity of the antibodies was different. Immunoperoxidase assays were used to determine if antibodies 104 and/or 142 could detect BIV replication in cell culture. Both antibodies were found to react with BIV-induced syncytia and individual BIV-infected cells. The antibodies were also used successfully in a focal immunoassay for quantitation of BIV-infected cells. These antibodies will provide valuable reagents for detection and quantitation of BIV replication in studies of viral pathogenesis and immunity.

Animals↗
PubMed1990

Transcervical fractures of the hip treated with the Bateman bipolar prosthesis.

Eighty-seven elderly patients with subcapital hip fractures treated by Bateman bipolar hip hemiarthroplasty were reviewed using Harris hip scores at a minimum of 24 months after their index operation. The complication rate was comparable to other reported series. The degree of pain was lower than a comparable unipolar arthroplasty series. Neither the relationship of the stem to the canal nor the presence of bone graft in the stem fenestration had any correlation to the patients' function. Femoral cups too large for the acetabulum predictably required another operation, but normal or small cup relationships had no prognostic correlation.

Aged↗
PubMed1988

A stool collection device: the first step in occult blood testing.

Despite widespread fecal blood testing, the technique of gathering stool for sampling has remained uncontrolled. We sought to describe how patients have contended with this awkward step, to study artifact caused by toilet water, and to construct a collection device that prevents sampling problems. A survey of 250 patients showed that most (56%) had retrieved stools from the toilet basin, 17% used a pan or other household receptacle, 10% used newspaper or tissue paper, and 17% had been unable or unwilling. Sampling stool from the toilet basin introduces error because 4% to 75% of blood leaches from the fecal surface into surrounding water after only 4 to 12 minutes, and many toilet sanitizers cause false-positive guaiac reactions. We describe an inexpensive, disposable stool collector; outpatient compliance has been 97% using this device. To avoid biochemical artifact and facilitate stool sampling, we advocate that a collection device be incorporated into the occult blood testing process.

Adult↗
PubMed1985

Radiology of fracture-dislocation of the cervical spine during delivery.

Four infants with fracture-dislocation of the cervical spine after traumatic delivery are described. In one patient with tetraparesis and complete dislocation of the cervical spine, transection of the cord at C6 was shown at autopsy. Two patients had fractures through the superior cartilaginous plates of the vertebral body with anterior subluxation of the spine. A fourth patient had a vertical fracture through the body of C5 with tracheal compression secondary to anterior dislocation of the spine. With conservative therapy, these three patients had good clinical recovery with healing and remodeling of the fractured vertebrae.

Birth Injuries↗
PubMed1977

Rabbit globin mRNA: analysis of T1 RNAse digestion fragments.

Rabbit globin complementary DNA made with RNA-dependent DNA polymerase (reverse transcriptase) was used as a template for in vitro synthesis of 32P-labeled RNA and deoxysubstituted RNA. The sequences of the nucleotides in most of the fragments resulting from combined ribonuclease T1 and alkaline phosphatase digestion have been determined. In addition, the 3' nearest neighbor was determined for several fragments resulting from digestion with T1 ribonuclease. The utility of the deoxysubstitution technique was demonstrated by the ease with which the sequences of pyrimidine-rich fragments could be determined. Many sequences thus determined were long enough to fit uniquely with the alpha- or beta-globin amino acid sequences. The positions of these fits were found to be clustered, leading us to believe that only certain regions of the complementary DNA are transcribed by Escherichia coli RNA polymerase. Other unique characteristics of RNA synthesis from a complementary DNA template include a high yield of free poly(A) and the fact that one must use low rather than high salt buffers to obtain transcripts of high molecular weight.

Amino Acid Sequence↗
PubMed1975

Human polymorphonuclear leucocyte migration inhibitory factor. Evidence for antigen dependency.

Sudies were performed on human polymorphonuclear leucocyte migration inhibitory factor (PMN-MIF) to determine its antigen dependence. PMN-MIF produced by lymphocytes in response to purified protein derivative or coccidiodin was measured in an agarose gel system with buffy coat leucocytes as indicator cells. PMN-MIF activity contained in the lymphocyte supernatants uniformly disappeared when the supernatants were diluted 1:50 with medium; the inhibitory activity was only restored when the diluted supernatants were reconstituted with specific antigen. PMN-MIF isolated by polyacrylamide gel electrophoresis showed the same properties as PMN-MIF present in whole supernatants. This factor consistently migrated in the albumin region on gel electrophoresis. These data indicate that human PMN-MIF is antigen-dependent.

Antigens↗
PubMedDate not supplied

Scleroderma of the foot: orthopaedic treatment.

Four patients with scleroderma involving the feet have been treated at Childrens Hospital of Los Angeles by the authors. All children had severe deformity of the feet secondary to the scleroderma. A review of the literature reveals little past mention of indications or treatments of this deformity in the past with the exception of the use of local steroids. Six feet in four children underwent orthopedic treatment. Treatment was primarily by casting to stretch soft tissues and gain as much correction as possible. Surgical correction of the remaining deformity by releasing the soft tissue contractures was then accomplished. Internal fixation of the foot in the corrected position was carried out in four cases. Three of the four patients showed significant improvement following soft tissue surgery and one patient was unchanged. Surgical treatment of the patient with scleroderma can be carried out safely as long as careful attention is paid to circulatory status and extensive preoperative casting and stretching of "soft" tissues is utilized.

Casts, Surgical↗
PubMedDate not supplied

A respirator alarm.

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Electronics, Medical↗