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Biomedical subjects

M Posner

Publications and source records attributed to M Posner.

At least 37 records · Page 2Linked to original sources
PubMed1996

Human antibody variable region gene usage in HIV-1 infection.

Human antibody variable region gene usage during human immunodeficiency virus type 1 (HIV-1) infection is examined in the following review, and several hypotheses are presented to account for the distinct patterns of antibody gene expression associated with infection. Evidence supporting qualitatively biased antibody gene expression has been derived from analysis of the human humoral immune response by isoelectric focusing (IEF) and serological and molecular studies of immunoglobulin (Ig) from different lymphoid compartments of HIV-1-infected patients. Preferential usage of heavy-chain variable region (VH) gene families 1 and 4 is supported by serological studies of serum Ig and molecular characterization of anti-HIV-1 human monoclonal antibodies derived from infected patients. Negative biases against VH3 family gene usage are detected by polymerase chain reaction (PCR) studies of peripheral blood lymphocytes from AIDS patients but not by combinatorial phage display library techniques. Biased antibody gene usage and expression during HIV-1 infection may be related to HIV-1 pathogenesis by limiting the available HIV-1 neutralizing repertoire. Further molecular characterization of anti-HIV-1 antibodies and in vivo expression of V-region genes during HIV-1 infection should provide important information regarding antibody gene expression and its relationship to HIV-1 pathogenesis.

Antibodies, Monoclonal↗
PubMed1995

A dose-response study of the efficacy and safety of ipratropium bromide nasal spray in the treatment of the common cold.

Rhinorrhea is an annoying symptom of the common cold for which effective therapy is not currently available. Ipratropium bromide (IB) is an anticholinergic drug that has been shown to decrease glandular secretion when applied topically to the nasal mucosa. The purpose of this study was to compare the efficacy and safety of three doses of IB nasal spray versus either vehicle or no treatment in relieving rhinorrhea in patients with naturally acquired colds. Rhinorrhea severity was measured objectively by determining nasal discharge weights and subjectively by means of visual analog scale scores. Compared with either vehicle or no treatment, IB nasal spray produced a significant decrease in the severity of rhinorrhea. A dose of 84 micrograms (two sprays of a 0.06% solution in buffered saline solution) in each nostril was more efficacious than a 42 microgram per nostril dose and only marginally less efficacious than a 168 micrograms per nostril dose. The 84 micrograms per nostril dose also was associated with fewer adverse events than was the higher dose. None of the adverse events related to intranasal IB therapy was of a serious nature. The use of IB nasal spray appears to be a rational and safe approach to relieving rhinorrhea associated with the common cold.

Adolescent↗
PubMed1995

Cisplatin and chronic oral etoposide as salvage therapy for advanced colorectal carcinoma.

Patients with metastatic colorectal carcinoma who have failed 5-fluorouracil-based chemotherapy have no effective second-line treatment available. Recent studies demonstrating clinical synergy between cisplatin and etoposide, and others exploring the efficacy of etoposide regimens utilizing chronic oral administration, suggested the utility of a new regimen incorporating these elements to treat refractory colorectal carcinoma. Fourteen patients were treated with weekly cisplatin and daily oral etoposide for 21 days in cycles of 28-35 days. Toxicity was significant, both hematologic and gastrointestinal in these pretreated patients. There were no objective responses, and median survival was 9.5 months. Weekly cisplatin and daily oral etoposide are poorly tolerated and ineffective in the treatment of refractory colorectal carcinoma. Further studies are needed to discover effective therapy for this disease.

Adenocarcinoma↗
PubMed1995

Simple enzyme immunoassay for titration of antibodies to the CD4-binding site of human immunodeficiency virus type 1 gp120.

We report the development of an immunoassay for the titration of antibody to the CD4-binding site (CD4BS) of the human immunodeficiency virus type 1 (HIV-1) surface glycoprotein gp120. This assay is a competitive enzyme-linked immunosorbent assay in which serum antibodies compete with labeled F105, a human monoclonal antibody whose corresponding epitope overlaps the conformation-dependent CD4BS, for binding to purified recombinant gp120 coated on a solid phase. Ninety-nine percent (109 of 110) of HIV-1-positive French patients and 91% (51 of 56) of HIV-1-positive African patients had CD4BS antibodies, indicating that the conformational CD4BS epitope is well conserved among different subtypes of HIV-1. Titers of CD4BS antibodies according to clinical status appeared to be not statistically different. A longitudinal study in 21 seroconverters showed that, for the majority of individuals, CD4BS antibodies appeared early and persisted at relatively high titers for several years. None of 21 HIV-2-seropositive patients had CD4BS antibodies in our assay, suggesting that the antibodies produced during HIV-2 infection are not cross-reactive with the CD4BS of HIV-1 gp120.

Amino Acid Sequence↗
PubMed1995

Vertical Transmission of HIV-1. Correlation with maternal viral load and plasma levels of CD4 binding site anti-gp120 antibodies.

Almost all childhood HIV-1 is now acquired through vertical transmission. Identifying factors that affect the rate of transmission may lead to the initiation of specific preventive strategies. In this study, antibody levels against different neutralizing epitopes on the envelope glycoprotein of HIV-1 (gp120) were measured in HIV-1-infected pregnant women that either transmitted HIV-1 to their infants (18 women) or did not (29 women). Differences in levels of antibodies directed against the monomeric gp120 molecule and against the V3 loop region of gp120 were not significantly different between the two groups studied. However, significant differences were observed in the levels of CD4 binding site antibodies, as determined by the ability of diluted maternal plasma to inhibit binding of the CD4 binding site monoclonal antibody F105 (mAb F105) to monomeric gp120. In addition, more nontransmitting mothers had low viral load as defined by having two or more negative HIV-1 viral cultures during pregnancy compared with transmitters. This pilot study suggests that in addition to higher viral load, low levels of CD4 binding site antibodies correlate with increased risk of HIV-1 vertical transmission. Passive immunotherapy with broadly neutralizing CD4 binding site antibodies should be considered as a strategy to reduce this risk.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Concurrent cis-platinum and radiation with or without surgery for advanced head and neck cancer.

PURPOSE: This study was undertaken to assess the efficacy of concurrent cis-platinum and radiation in patients with advanced head and neck cancer and to determine if patients responding to the preoperative regimens may be cured without radical surgery. METHODS AND MATERIALS: One hundred and one patients with potentially operable Stage III and IV squamous cell carcinoma of the head and neck received 45 Gy at 1.8 Gy fractions and continuous infusion cis-platinum 20 mg/m2 over 24 h on days 1 through 4 and 22 through 25 of the radiation schedule. Three to 4 weeks later, radical surgery of the primary site and neck dissections for patients presenting with cervical adenopathy was undertaken or if a complete response had been achieved, continued with radiation to 72 Gy with another course of concurrent continuous infusion cis-platinum. RESULT: Complete and partial responses were achieved in 92% of the primary sites and 95% of the nodes. Over 80% of the patients were rendered tumor free at surgery after only the initial course of chemotherapy and radiation. There were no grade 3 or 4 toxicities from chemotherapy and radiation. Ninety-five percent of the patients who initiated treatment completed it. With a median follow-up of 41 months for all patients, 49% of the patients have survived disease free up to 9 years, independent of whether or not their primary tumors were resected or were treated definitively by further chemotherapy sensitized radiation. The disease-specific survival is 78% after 3 years with no local failures thereafter. CONCLUSION: These findings suggest that continuous infusion cis-platinum administered concurrently with radiotherapy can improve survival in advanced head and neck cancer. Patients responding to the preoperative regimen may be cured without radical surgery, which can be reserved for salvage.

Actuarial Analysis↗
PubMed1994

Anaesthesia for caesarean section in a patient with Watson's syndrome.

Watson's syndrome is an uncommon genetic disorder whose features include mental retardation and pulmonary valvular stenosis. The purpose of this report is to describe one management strategy used successfully to anaesthetize a woman with this disorder who presented for Caesarean section. Epidural anaesthesia using 0.5% bupivacaine without epinephrine in 2-3 ml boluses to a total dose of 15 ml was administered over 30 min. Invasive haemodynamic monitoring in the form of arterial and central venous catheters were used to guide therapy and help ensure maternal and fetal well-being. Intravenous ketamine in doses of 10-20 mg every five minutes to a total dose of 245 mg (4.5 mg.kg-1) was used to overcome the patient's uncooperative nature and facilitate invasive procedures. Postoperative analgesia was provided using 3 mg epidural morphine. The patient was observed in the intensive care unit for the first postoperative day and experienced an uncomplicated intra- and postoperative course. We conclude that this technique represents a safe and effective method for anaesthetizing patients with this complicated problem for Caesarean section.

Adult↗
PubMed1994

Smooth pursuit eye movements with imaginary targets defined by extrafoveal cues.

Initiation of smooth pursuit eye movements was studied using imaginary targets defined by pairs of small spots ("cues") moving together in step-ramp motion. The arrangement of cues and imaginary target were either "two-sided"--cues far apart and imaginary target midway between, or "one-sided"--cues 4 deg apart and imaginary target to one side of the cue pair. (1) Pursuit of two-sided stimuli was much better than pursuit of one-sided stimuli and was often as good as pursuit of a real foveal target. (2) Experiments with various cue configurations suggest an attribute required for vigorous pursuit: "foveal enclosure". Configuration information is available to the pursuit system immediately after the onset of motion. (3) Pursuit of imaginary targets is markedly degraded by a background; the effect is strongest for a background at the fovea and weaker for an eccentric background, including one at the cue location.

Cues↗
PubMed1994

A prospective randomized trial of total parenteral nutrition after major pancreatic resection for malignancy.

OBJECTIVES: The authors examined the impact of adjuvant total parenteral nutrition after major pancreatic resection for malignancy. SUMMARY BACKGROUND DATA: Previous studies have suggested a benefit to perioperative nutritional support for patients undergoing major gastrointestinal surgery. METHODS: A prospective, randomized study was conducted using patients who had undergone a major pancreatic resection with randomization on postoperative day one to either receive or not receive adjuvant total parenteral nutrition. RESULTS: No benefit could be demonstrated by the use of adjuvant parenteral nutrition in this setting. Complications were significantly greater in the group receiving total parenteral nutrition. These complications tended to be those associated with infection. CONCLUSIONS: Routine applications of postoperative parenteral nutrition to patients undergoing major pancreatic resection for malignancy cannot be recommended. Further studies are required to determine the reason that infectious complications in these patients are increased.

Aged↗
PubMed1994

Resistance to neutralization by broadly reactive antibodies to the human immunodeficiency virus type 1 gp120 glycoprotein conferred by a gp41 amino acid change.

A neutralization-resistant variant of human immunodeficiency virus type 1 (HIV-1) that emerged during in vitro propagation of the virus in the presence of neutralizing serum from an infected individual has been described. A threonine-for-alanine substitution at position 582 in the gp41 transmembrane envelope glycoprotein of the variant virus was responsible for the neutralization-resistant phenotype (M.S. Reitz, Jr., C. Wilson, C. Naugle, R. C. Gallo, and M. Robert-Guroff, Cell 54:57-63, 1988). The mutant virus also exhibited reduced sensitivity to neutralization by 30% of HIV-1-positive sera that neutralized the parental virus, suggesting that a significant fraction of the neutralizing activity within these sera can be affected by the amino acid change in gp41 (C. Wilson, M. S. Reitz, Jr., K. Aldrich, P. J. Klasse, J. Blomberg, R. C. Gallo, and M. Robert-Guroff, J. Virol. 64:3240-3248, 1990). It is shown here that the change of alanine 582 to threonine specifically confers resistance to neutralizing by antibodies directed against both groups of discontinuous, conserved epitopes related to the CD4 binding site on the gp120 exterior envelope glycoprotein. Only minor differences in binding of these antibodies to wild-type and mutant envelope glycoproteins were observed. Thus, the antigenic structure of gp120 can be subtly affected by an amino acid change in gp41, with important consequences for sensitivity to neutralization.

Animals↗
PubMed1994

Phase II study of topotecan in metastatic non-small-cell lung cancer.

PURPOSE: Topotecan is an inhibitor of topoisomerase I that has shown preclinical activity against non-small-cell lung cancer (NSCLC). This phase II study was designed to determine the clinical activity and toxicity spectrum of topotecan in untreated patients with metastatic NSCLC. PATIENTS AND METHODS: Twenty previously untreated patients received topotecan every 21 days at the dose of 2 mg/m2/d intravenously (IV) for 5 days for two cycles, at which point response was assessed. Patients with either clinical response or stable disease (SD) received additional cycles of the drug until toxicity developed or disease progression (PRG) occurred. RESULTS: This study was designed to enter 30 patients. However, because no clinical responses were seen in the first 20 patients entered onto the study, the early-stopping rule was invoked and patient accrual was halted. Eleven patients (55%) had SD on topotecan, and nine (45%) had PRG. Toxicity included neutropenia and rash. The median survival duration for all patients was 7.6 months. CONCLUSION: We observed no objective clinical responses despite producing high-grade neutropenia. Phase II trials of topotecan using different schedules or higher doses supported by growth factors may clarify the role of topotecan in the treatment of NSCLC. The combination of topotecan with cisplatin and topoisomerase II inhibitors such as etoposide should be explored. Finally, the median survival duration of 7.6 months for 20 patients treated with an agent that failed to produce any obvious clinical responses compares favorably to the survival obtained with combinations of existing agents. This supports the further study of novel compounds in this clinical setting.

Aged↗
PubMed1994

Induction with OKT3 and prostaglandin E1 in liver transplantation.

Forty-six consecutive adult patients underwent 51 orthotopic liver transplants in a prospective study to evaluate sequential induction with ORTHOCLONE OKT3 (muromonab-CD3), prostaglandin E1, cyclosporine, azathioprine, and methylprednisolone. Infection prophylaxis included preoperative bowel preparation and ganciclovir if cytomegalovirus was diagnosed in either donor or recipient. All rejection episodes were documented by liver biopsy before treatment. Seventy-four percent of patients evaluable beyond 1 year have had no rejection episodes. The retransplant rate was 10%, with a 4% primary nonfunction rate. There was no rejection of grafts that could not be retreated with OKT3. Forty-two percent (5 of 12) of rejection episodes responded to steroid recycling alone. The infection rates for all patients at 1 year were 54% bacterial, 17% fungal, and 22% viral. Three septic deaths were attributed to overimmunosuppression. Two-year patient and graft survival rates were 80% and 72%, respectively. This OKT3 induction protocol results in limited rejection episodes without increasing infections, yielding an acceptably low rate of graft loss.

Adult↗
PubMed1994

Androgen receptor immunohistochemistry on paraffin-embedded tissue.

Androgen deprivation remains the primary therapy for patients with metastatic prostate cancer. Response to hormonal manipulation, however, has been quite variable. Androgen receptor (AR) expression has been used to predict clinical response to antiandrogenic treatment. However, methods of detection of AR expression have been limited to receptor biochemical assays in cytosolic or nuclear fractions of frozen tissue homogenates with obvious contamination problems by nonmalignant epithelial and stromal cells. As a result, studies correlating AR expression with response to hormonal therapy have been limited and controversial. More recently, immunohistochemical methods of analysis have become available, but only on frozen tissue. We describe a simple method to evaluate ARs on formalin-fixed, paraffin-embedded tissue sections using antigen retrieval methods. Primary, as well as metastatic, prostate carcinomas showed nuclear staining for ARs. Secretory cells stained uniformly in hyperplastic and normal prostatic glands. The majority of stromal cells had strong nuclear positivity. All other cancers tested (colon, breast, lung, skin, kidney) were negative. This immunohistochemical technique allows evaluation of prostate cancer AR status in routinely processed tissues. Thus, application of this technology to archival material should permit assessment of whether AR expression is predictive of response to endocrine therapy in advanced prostate cancer.

Adenocarcinoma↗
PubMed1993

Neoadjuvant therapy for unresectable pancreatic adenocarcinoma.

The purposes of this study were to determine whether continuous infusion of fluorouracil combined with external-beam radiation therapy improved the resectability and survival of patients with pancreatic carcinoma. Sixteen patients with unresectable disease confined to the pancreas and celiac nodes were treated, and their outcome was compared with that of 24 patients with potentially resectable disease who were treated concurrently. The neoadjuvant therapy was completed with acceptably few toxic effects but with only a minor decrease in tumor size. Two patients underwent resection and remained free of disease 20 and 22.5 months later. However, the median survival of the entire neoadjuvant group was 8 months. All 24 patients with potentially resectable carcinoma underwent surgical exploration. Fifteen of the 24 patients underwent resection and survived a median of 12.5 months. Neoadjuvant chemoradiation may have improved outcome and resectability for two (12.5%) of 16 patients with unresectable pancreatic carcinoma, but more effective therapy options must be developed to improve outcome.

Adenocarcinoma↗
PubMed1993

Synergistic inhibition of HIV-1 by CD4 binding domain reagents and V3-directed monoclonal antibodies.

Human immunodeficiency virus (HIV) binds to the surface of CD4 positive lymphocytes and monocyte/macrophages via a high affinity interaction between CD4 and the HIV envelope glycoprotein gp120 and is internalized by fusion of the virus and the cell membrane. The third variable (V3) domain of gp120 also plays a central role in the fusion and viral entry process. Reagents that neutralize HIV by binding to the CD4 binding domain or V3 domain of gp120 have been proposed as therapeutics in the post-HIV exposure and perinatal setting. However, the neutralization potency of these proposed reagents, sCD4, V3 directed and CD4 binding domain directed monoclonal antibodies (MAbs), is intermediate at best and may be of limited use in a clinical setting. We have demonstrated that the combination of reagents to these two primary targets for neutralization resulted in synergy with 10- to 1000-fold increase in virus neutralization. The addition of these combined reagents a second time 3 and 5 days postinfection resulted in an additional 10-fold increase in neutralization suggesting a block in HIV spread from cell to cell. These data suggest that a combination of CD4 binding domain reagents and V3 antibody infused at intervals may significantly reduce the viral load in AIDS patients.

Animals↗
PubMed1993

Combined modality therapy for stage IIIA non-small cell carcinoma of the lung.

53 patients with stage IIIA non-small cell carcinoma of the lung (NSCCL) were treated with multimodality therapy consisting of induction radiotherapy (55.8 Gy) and two cycles of concurrent chemotherapy with cisplatin, 25 mg/m2 for 4 days by continuous infusion and bolus etoposide, 100 mg/m2 on days 2 and 4 of each cycle followed by surgery and adjuvant chemotherapy. Of 53 evaluable patients, 47 achieved clinical responses (9 complete response, 38 partial response) after induction therapy for a response rate of 89%. 47 patients were resectable after induction therapy, but 8 patients refused surgery and 6 patients were not eligible for surgery based on poor pulmonary function (medical contraindications). 33 patients underwent thoracotomy and in 6 patients, resection was technically unfeasible. Thus complete surgical resection was accomplished in 27 patients. After all therapy, 28 patients achieved a complete response (53%) and 19 patients a partial response (36%). Toxicities were mild. At a maximum of 75 months (median, 28 months) of follow-up, the median survival of the entire group is 24 months. The median survival of resected patients has not been reached; their 6-year survival rate is 55%. Unresected patients survived for a median of 11 months. This multimodality regimen is well-tolerated, induces a high response and resectability rate and prolongs survival in resected patients.

Adult↗