PubMed Health⌕ Search

Biomedical subjects

H Stern

Publications and source records attributed to H Stern.

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

55-base pair deletion in certain patients with Gaucher disease complicates screening for common Gaucher alleles.

Mutations in the glucocerebrosidase gene which result in Gaucher disease can originate from the highly homologous glucocerebrosidase pseudogene. A 55-bp deletion in exon 9, which corresponds to a 55-bp segment absent from the pseudogene, has been identified in patients with Gaucher disease. We have developed a simple polymerase chain reaction (PCR)-based method to detect this 55-bp deletion, and have found this mutation in 3 of 75 DNA samples (4%) collected from patients with Gaucher disease. Commonly used PCR-based screening methods for specific Gaucher mutations frequently make use of primers either within or surrounding the 55-bp gap to selectively distinguish the glucocerebrosidase gene from the pseudogene. However, if the 55-bp deletion in exon 9 occurs, primers will either fail to produce an amplification product or will produce a shortened product which will be falsely attributed to the pseudogene. This could lead to inaccurate genotyping and genetic counseling for some Gaucher patients and their families. We therefore recommended that laboratories using PCR-based screening techniques involving primers in this region initially determine whether this 55-bp sequence is present.

Alleles↗
PubMed1996

Cytotoxicity of B72.3XOKT3 bispecific antibody recognizing human colon cancer.

Bispecific monoclonal antibodies can be used to redirect peripheral blood lymphocytes against tumor cells. In the present study, a murine bispecific monoclonal antibody was developed using somatic hybrydization. The antibody has two different binding arms: one arm directed against human CD3 receptor expressed on T-lymphocytes and the other against tumor associated glycoprotein TAG-72, expressed on human carcinomas, such as colon, breast, and pancreas. Partially purified antibody was capable of inducing human T-cell proliferation and preventing growth of colon cancer cell line in nu/nu mice in a tumor neutralization assay.

Animals↗
PubMed1996

Natural history of aberrant crypt foci. A surgical approach.

BACKGROUND: The aberrant crypt focus (ACF) appears to be an important early step in colorectal carcinogenesis. Our objectives were to determine the natural history of ACF in a surgical model. METHODS: The natural history of ACF was followed by marking the lesions in vivo with tattoos. Rats were given four weekly injections of azoxymethand (AOM; 20 mg/kg). One hundred days after the first injection of AOM, rats were anesthetized, and individual aberrant crypt focus was identified by staining with methylene blue. A 3 x 3 mm area, identifying one large (4-8 crypts) ACF was marked with a tattoo dye in each colon. Control animals received saline or AOM injections and were tattooed in areas without ACF. At 200 days, colons were examined for the presence of macroscopic lesions. RESULTS: A total of 54 tumors were found in the study group of 38 animals, and 21 of these were in the transverse and proximal descending colon. The marked areas (all in transverse and proximal descending colon) yielded 6 tumors and 2 ACF, but in 30 instances no abnormality was noted. Probability of observing a tumor in the 3 x 3 mm area of the colon that was identified as containing ACFs was 17 times greater than expected from the observed tumor rate in approximately the same zone (16 vs. 1.7 percent; 95 confidence interval, 10 to 22 and 0.5 to 1.3 percent). Twenty control animals receiving saline had no tumors of epithelial origin. Nine control animals that were carcinogen-treated and tattooed in areas without ACF had no tumors in the marked areas. CONCLUSION: Results thus show regression of many ACF identified early in the carcinogenesis process. Results also support the hypothesis that some ACF are precursor lesions for adenomas and cancers.

Adenoma↗
PubMed1995

Treatment of rectovaginal fistulas that has failed previous repair attempts.

PURPOSE: The purpose of this study was to assess results of treatment of rectovaginal fistulas (excluding pouch vaginal fistulas) that have failed previous attempts at repair. METHOD: A retrospective chart review of all patients presenting with nonhealing rectovaginal fistula was performed. RESULTS: Twenty eight patients with persistent fistulas were identified. In 18 patients the fistula was classified as simple, and in 10 the fistula was complex. Fourteen fistulas were secondary to obstetric injury, five were caused by Crohn's disease, and nine patients had miscellaneous etiologies for their fistulas. Of patients with persistent simple fistulas, 13 (72 percent) of the fistulas healed, 5 after advancement flaps, 5 following sphincteroplasty, and 3 after coloanal anastomoses. Of persistent complex fistulas, only four of ten (40 percent) healed, one following sphincteroplasty, one with coloanal anastomosis, and two after gracilis transposition. A total of 23 advancement flaps were done in 17 patients with five fistulas healing (29 percent). Sphincteroplasty and fistulectomy was successful in six of seven patients (86 percent). Coloanal anastomosis resulted in healing of four of six patients (67 percent) in whom it was attempted. Gracilis muscle transfer was successful in two of two patients (100 percent). CONCLUSION: Persistent rectovaginal fistula presents a difficult management problem. Choice of operation must be tailored to the underlying pathology and type of repair previously done. Advancement flap repair is generally not recommended for persistent complex fistulas or for simple fistulas that have failed a previous advancement flap repair.

Adult↗
PubMed1995

Genetic and biochemical normalization in female carriers of Duchenne muscular dystrophy: evidence for failure of dystrophin production in dystrophin-competent myonuclei.

We studied 19 symptomatic female carriers of the Duchenne muscular dystrophy (DMD) gene. Most of these dystrophinopathy patients had had an erroneous or ambiguous diagnosis prior to dystrophin immunofluorescence testing. We assessed clinical severity by a standardized protocol, measured X-chromosome inactivation patterns in blood and muscle DNA, and quantitated the dystrophin protein content of muscle. We found that patients could be separated into two groups: those showing equal numbers of normal and mutant dystrophin genes in peripheral blood DNA ("random" X-inactivation), and those showing preferential use of the mutant dystrophin gene ("skewed" X-inactivation). In the random X-inactivation carriers, the clinical phenotype ranged from asymptomatic to mild disability, the dystrophin content of muscle was > 60% of normal, and there were only minor histopathologic changes. In the skewed X-inactivation patients, clinical manifestations ranged from mild to severe, but the patients with mild disease were young (5 to 10 years old). The low levels of dystrophin (< 30% on average) and the severe symptoms of the older patients suggested a poor prognosis for those with skewed X-inactivation, and they all showed morphologic changes of dystrophy. The random inactivation patients showed evidence of biochemical "normalization," with higher dystrophin content in muscle than predicted by the number of normal dystrophin genes. Seventy-nine percent of skewed X-inactivation patients (11/14) showed genetic "normalization," with proportionally more dystrophin-positive nuclei in muscle than in blood. In 65% of the skewed X-inactivation patients, dystrophin was not produced by dystrophin-positive nuclei; an average of 20% of myofiber nuclei were genetically dystrophin-positive but did not produce stable dystrophin. Biochemical normalization seems to be the main mechanism for rescue of fibers from dystrophin deficiency in the random X-inactivation patients. In the skewed X-inactivation patients, genetic normalization is active, but production failure of dystrophin by dystrophin-normal nuclei may counteract any effect of biochemical normalization. In the skewed X-inactivation patients, the remodeling of the muscle through cycles of degeneration and regeneration led to threefold increase in the number of dystrophin-competent nuclei in muscle myofibers (3.3 +/- 4.6), while dystrophin content was on the average 1.5-fold less then expected (-1.54 +/- 3.38). Our results permit more accurate prognistic assessment of isolated female dystrophinopathy patients and provide important data with which to estimate the potential effect of gene delivery (gene therapy) in DMD.

Adult↗
PubMed1995

Problems of delivery of monoclonal antibodies. Pharmaceutical and pharmacokinetic solutions.

Monoclonal antibodies to tumour-associated antigens have great theoretical potential for the specific targeting of radioactivity and anti-neoplastic agents to tumours. The clinical success of monoclonal antibody-based cancer diagnosis and therapy depends, however, on solving a number of pharmacokinetic delivery problems. These include: (i) slow elimination of monoclonal antibodies from the blood and poor vascular permeability; (ii) low and heterogeneous tumour uptake; (iii) cross-reactivity with normal tissues; (iv) metabolism of monoclonal antibody conjugates; and (v) immunogenicity of murine forms in humans. As a result of extensive pharmaceutical and pharmacokinetic research conducted over the past 10 to 15 years, several potential solutions to these delivery problems have been identified. Blood concentrations of antibody conjugates may be reduced through regional administration, the use of antibody fragments, interventional strategies and various pre-targeting techniques. Tumour uptake may be increased through administration of higher doses, or the use of agents to increase tumour vascular permeability. Tumour retention of antibody conjugates may be improved by inhibition of metabolism, by using more stable linkage chemistry. Alternatively, normal tissue retention may be decreased through the use of metabolisable chemical linkages inserted between the antibody and conjugated moiety. Very small antigen-binding fragments and peptides that exhibit improved tumour penetration and more rapid elimination from the blood and normal tissues have been prepared by genetic engineering techniques. Chimeric (mouse/human) and human monoclonal antibodies have been developed to circumvent the problem of immunogenicity. Future research will continue to be focused on improvements in the design of monoclonal antibodies for tumour targeting, with the ultimate goal of finally uncovering the 'magic bullet' envisioned by Paul Ehrlich almost a century ago.

Animals↗
PubMed1994

Characterization of two novel adenomatous polyposis coli (APC) gene mutations in patients with familial adenomatous polyposis (FAP).

Patients with Familial Adenomatous Polyposis (FAP) manifest numerous colorectal adenomas as well as benign and malignant extra-colonic lesions. Adenomatous polyposis coli (APC) gene mutations are the underlying genetic defect in FAP. We analyzed germline DNA of 81 unrelated FAP patients and evaluated correlation of APC mutation genotype and clinical phenotype. Germline APC mutations were identified in 18 FAP patients including two novel 2 bp deletions at APC codons 1067 and 1259. FAP patients were screened for hypertrophic ocular fundus lesions, desmoids and peri-ampullary adenomas. As reported previously (Olshwang et al 1993b), a positive correlation for the frequency of retinal lesions and germline APC mutation was observed among all FAP patients except one. No significant correlation was observed for APC mutation genotype and the occurrence of desmoids and peri-ampullary adenomas. Genetic factors contributing to familial segregation of these lesions need further investigation.

Adenomatous Polyposis Coli↗
PubMed1994

Colorectal tumourigenesis.

Colorectal cancer is significant because of its lethality and high incidence in the Western world. Furthermore, it is a particularly suitable model for studying the events involved in the progression from normal tissue to invasive cancer. There is a great deal of epidemiological and histopathologic evidence to implicate the adenomatous polyp as the precursor to colorectal cancer. Moreover in recent years investigators have uncovered some of the molecular genetic events that underlie the progression from normal epithelium to polyp to cancer. It is hoped that an increased understanding of the molecular changes will afford opportunities for new diagnostic, prognostic and therapeutic strategies in the management of this disease.

Adenoma↗
PubMed1994

Immunoscintigraphy of human colon cancer xenografts in nude mice using a second-generation TAG-72 monoclonal antibody labelled with 99Tcm.

Monoclonal antibody CC83 is a second-generation high-affinity antibody directed against the TAG-72 antigen in colorectal cancer. Our objectives were to evaluate the biodistribution, pharmacokinetics and imaging properties of CC83 labelled with 99Tcm via a modified Schwartz technique. The immunological integrity of 99Tcm-CC83 was evaluated by size-exclusion FPLC and by determining the immunoreactive fraction in vitro against bovine submaxillary mucin. The biodistribution of 99Tcm-CC83 up to 24 h postinjection was evaluated in nude mice bearing subcutaneous LS174T human colon cancer xenografts. Blood radioactivity data was fitted to a one-compartment pharmacokinetic model. Images of tumour-bearing mice were obtained at 17-24 h postinjection with 99Tcm-CC83. 99Tcm-CC83 was eluted as intact immunoglobulin by FPLC analysis and the mean immunoreactive fraction was 0.49 +/- 0.15. Tumour uptake at 24 h postinjection was 11.2 +/- 4.1% i.d.g-1. Radioactivity in the blood was eliminated rapidly with a half-life of 8 h and tumour:blood ratios were > 2:1 at 24 h postinjection. LS174T tumours were successfully imaged in 3/3 mice. In vitro studies showed instability of 99Tcm-CC83 when challenged with cysteine and glutathione but not metallothionein, suggesting a metabolic route for the 99Tcm antibody in vivo. We conclude that CC83 labelled directly with 99Tcm retains its immunological integrity and capability specifically to target subcutaneous LS174T human colon cancer tumours hosted in nude mice. These results further suggest that 99Tcm-CC83 may have potential for imaging colorectal cancer in humans.

Animals↗
PubMed1994

Detection of new paternal dystrophin gene mutations in isolated cases of dystrophinopathy in females.

Duchenne muscular dystrophy is one of the most common lethal monogenic disorders and is caused by dystrophin deficiency. The disease is transmitted as an X-linked recessive trait; however, recent biochemical and clinical studies have shown that many girls and women with a primary myopathy have an underlying dystrophinopathy, despite a negative family history for Duchenne dystrophy. These isolated female dystrophinopathy patients carried ambiguous diagnoses with presumed autosomal recessive inheritance (limb-girdle muscular dystrophy) prior to biochemical detection of dystrophin abnormalities in their muscle biopsy. It has been assumed that these female dystrophinopathy patients are heterozygous carriers who show preferential inactivation of the X chromosome harboring the normal dystrophin gene, although this has been shown for only a few X:autosome translocations and for two cases of discordant monozygotic twin female carriers. Here we study X-inactivation patterns of 13 female dystrophinopathy patients--10 isolated cases and 3 cases with a positive family history for Duchenne dystrophy in males. We show that all cases have skewed X-inactivation patterns in peripheral blood DNA. Of the nine isolated cases informative in our assay, eight showed inheritance of the dystrophin gene mutation from the paternal germ line. Only a single case showed maternal inheritance. The 10-fold higher incidence of paternal transmission of dystrophin gene mutations in these cases is at 30-fold variance with Bayesian predictions and gene mutation rates. Thus, our results suggest some mechanistic interaction between new dystrophin gene mutations, paternal inheritance, and skewed X inactivation. Our results provide both empirical risk data and a molecular diagnostic test method, which permit genetic counseling and prenatal diagnosis of this new category of patients.

Adolescent↗
PubMed1993

Local excision and post-operative radiation therapy for rectal carcinoma.

PURPOSE: To assess the patterns of failure and outcome following conservative surgery and post-operative radiation therapy for rectal cancer. METHODS AND MATERIALS: Twenty-five patients underwent post-operative radiation therapy (50 Gy in 20 fractions over 4 weeks) following local excision or electrocoagulation for carcinoma of the rectum. None of the patients had palpable residual disease following surgery. Selection factors for post-operative radiation therapy were refusal of a permanent colostomy, excessive operative risk of an abdominal perineal resection and concern regarding local control with conservative surgery alone. RESULTS: Six of 25 patients developed failure at the primary site. There was no lymph node failure. All five patients with primary failure alone underwent abdominal perineal resection and 2 remained free of recurrence. With a median follow-up of 6 years, 20 of 25 patients remained alive and free of disease. There was no apparent influence of age, sex, type of surgery, tumor size, distance of tumor from anal verge, tumor configuration, resection margins, integrity of the resected tissue, depth of invasion, differentiation, presence of lymphatic or vascular channel invasion, radiation dose or field size on local control and survival. One of 15 patients failed locally when the overall treatment time was 30 days or less, whereas 5 of 10 patients developed local failure when the overall treatment time exceeded 30 days. Sixteen of 20 patients in whom cancer did not recur retained normal anorectal function. All four patients with grade 3 early morbidity and the only patient with Grade 3 late morbidity were amongst the group of 13 patients treated with large AP-PA fields (mean: 15 x 19 cm2). CONCLUSION: In selected patients who are at high risk of local recurrence following local excision alone, and who refuse a colostomy or are at high operative risk from radical surgery, post-operative radiation therapy is an alternative to radical surgery.

Aged↗
PubMed1993

Treatment of peripheral bronchopleural fistulas with endobronchial occlusion coils.

Persistent peripheral bronchopleural fistulas can be difficult to manage. Endoscopic plugging of involved bronchi has been accomplished in a number of ways. We have devised a method of permanently blocking small peripheral airways using Gianturco vascular occlusion coils placed endobronchially by modified angiographic techniques. This procedure has been applied in 5 cases of complicated parenchymal air leaks. Complete or substantial partial control was achieved in all cases. There were no complications.

Adult↗
PubMed1993

The apolipoprotein E gene and the serum low-density lipoprotein cholesterol response to dietary fiber.

Our goal was to determine whether differences in apolipoprotein E (apo E) influenced the response to dietary changes aimed at reducing serum cholesterol levels, especially increases in fiber. Apo E phenotype and genotype were determined in 43 men and 24 women who had previously taken part in parallel 2-week metabolic dietary studies involving either wheat bran or oat bran supplementation at a level of 6.8 g fiber/1,000 kcal. Fasting blood lipid measurements had been made at the beginning and end of the 2-week metabolic period. Reductions in low-density lipoprotein (LDL) cholesterol levels across both oat and wheat bran diets were significantly different depending on the E allele (P = .048). The LDL cholesterol level reduction for E2 carriers (0.60 +/- 0.14 mmol/L, n = 13) was greater than that for E3 homozygotes (0.21 +/- 0.07 mmol/L, n = 38; P = .014) and E4 carriers (0.28 +/- 0.12 mmol/L, n = 16; P = .09). Only the change in dietary fiber on the oat bran diet was related significantly to the decrease in LDL cholesterol levels (r = -.47, P = .007; n = 32). No such relationship was seen on the wheat bran diet (r = -.010, P = .59; n = 33). Carriers of the E2 allele appear to be more responsive than noncarriers to a dietary change involving increased fiber intake. The data also support a lipid-lowering advantage of oat bran over wheat bran. Current dietary recommendations to reduce serum lipid levels may vary in effectiveness depending on distribution of apo E alleles in the different populations studied.

Adult↗
PubMed1993

Genetic variation associated with differences in the response of plasma apolipoprotein B levels to dietary fibre.

1. We hypothesized that differences within genes whose protein products are involved in apolipoprotein B metabolism could influence the response of plasma apolipoprotein B-containing lipoprotein concentrations to increases in dietary fibre. 2. We studied 67 subjects (43 men and 24 women) who had taken part in parallel 2 week metabolic dietary studies involving either wheat bran or oat bran supplementation. Fasting blood lipid, lipoprotein and apolipoprotein concentrations were measured at the start and end of the 2 week metabolic period. Genotypes were determined using DNA markers for the low-density lipoprotein receptor, apolipoprotein B, apolipoprotein CIII and hepatic lipase gene loci. 3. Reductions in plasma concentrations of apolipoprotein B were significantly different depending on genotype determined with a low-density lipoprotein receptor DNA marker (P = 0.03). There was no significant variation in the reduction of plasma total cholesterol, low-density lipoprotein cholesterol or apolipoprotein B concentrations for alleles of other genes tested. 4. Thus, genetic variability is associated with interindividual differences in the fibre-related reduction in plasma apolipoprotein B and apolipoprotein B-containing lipoprotein concentrations. Implementation of current dietary recommendations to reduce plasma lipoprotein levels with fibre may have variable effects in different individuals in part because of structural differences in candidate genes whose products are involved in lipoprotein metabolism.

Apolipoproteins B↗
PubMed1993

The use of lasers in colorectal cancer.

The potential addition of lasers to the armamentarium of physicians treating advanced colorectal cancer is welcome because of the morbidity associated with the disease and because of the limitations of standard treatments for some of the problems related to this common disease. However, laser treatment cannot be regarded yet as a standard modality. Questions still remain regarding the efficacy of these treatments in relieving the most troublesome symptoms of tenesmus and urgency, although bleeding and mucous discharge appear to be well controlled. Additional questions remain regarding expense and the relative benefits of lasers versus electrocoagulation (much cheaper) for rectal cancers. Other concerns relate to the learning curve involved with lasers, particularly for decompression of colonic obstructions, and efficacy compared to pneumatic dilatation.

Colorectal Neoplasms↗
PubMed1993

Radioimmunodetection of colorectal cancer metastases with 131I-labeled monoclonal antibody B72.3: a pilot study to determine efficacy of detection and pharmacokinetics.

We performed radioimmunoscintigraphy (RIS) and/or pharmacokinetic (PCK) studies in 12 patients with primary or metastatic colorectal carcinoma, utilizing an intravenous administration of 1-4 mCi (1 mg) of 131I-B72.3 monoclonal antibody. Metastatic lesions were correctly identified in 4/8 patients by RIS. Two patients with small lesions (> 2 cm diameter) had a false-negative RIS scan. Two patients had a true-negative RIS scan. Optimal images were obtained at 1 week postinjection. PCK studies showed that the plasma clearance of 131I-B72.3 was biexponential with an alpha-phase half-life ranging from 0.5 to 7.1 hr and a beta-phase half-life ranging from 47.5 to 85.3 hr. Systemic and renal clearance data indicated that 131I-B72.3 was cleared very slowly and almost entirely by deiodination. This pilot study was conducted to gain an understanding of the pharmacokinetics of this radiolabeled antibody. On the basis of these data, we are now studying second-generation antibodies as part of our long-range objectives to incorporate them in early detection and treatment protocols.

Adult↗