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Biomedical subjects

R M Hoffman

Publications and source records attributed to R M Hoffman.

At least 163 records · Page 9Linked to original sources
PubMed1991

In vitro sensitivity assays in cancer: a review, analysis, and prognosis.

Tumors are complex systems consisting of heterogeneous cancer cells as well as normal cells with each exhibiting unique drug sensitivity spectra. There have been many attempts to design in vitro systems to determine drug response to tumors. The most widely used system is the clonogenic assay. which has demonstrated some clinical predictivity. However, the clonogenic assay has been shown to have negative aspects, including low frequency of evaluation, clump artifacts, lack of cytotoxic end-points and disruption of normal cell-cell interactions existing in a true tissue environment. Newer models are described utilizing cytotoxic as well as cell-proliferation end-points, and maintenance of three-dimensional tissue architecture in vitro. It is concluded that less artifactual, more realistic models can be used to select more tumor-specific drugs which themselves in turn will make in vitro chemosensitivity assays more useful for cancer patients.

Cell Survival↗
PubMed1991

Diagnostic accuracy and clinical utility of thermography for lumbar radiculopathy. A meta-analysis.

The role of thermography for diagnosing lumbar radiculopathy was evaluated by literature review and meta-analysis. From 81 relevant citations, 28 studies could be analyzed for diagnostic-accuracy data (sensitivity and specificity) and method. Diagnostic-accuracy data varied significantly between studies; therefore meaningful pooled summary statistics could not be reported. Twenty-seven studies had major methodologic flaws including biased test interpretations, faulty cohort assembly, poor clinical descriptions, and small sample size. The only study of reasonably high quality found no discriminant value for liquid-crystal thermography. The role of thermography remains unclear. Rigorous clinical research is required to establish its diagnostic accuracy and clinical utility. Thermography cannot be recommended currently for routine clinical use in evaluating low-back pain.

Back Pain↗
PubMed1991

Serum and lavage lactate dehydrogenase isoenzymes in pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by the accumulation of lipoproteinaceous material in the alveolar space. Serum lactate dehydrogenase (LDH) has been noted to be elevated in patients with PAP in previous studies. We sought to extend this observation in a series of patients with PAP by looking at total serum LDH concentrations and LDH isoenzyme fractions measured before and after whole lung lavage. Total LDH and LDH isoenzymes were also determined in the lavage effluent. Total serum LDH was elevated before lavage in 10 of 16 patients. Prelavage serum LDH and prelavage alveolar-arterial O2 gradient showed a significant correlation (r = 0.62, p less than 0.05). A decrease in serum LDH was found after lavage in all patients in whom postlavage data was available (paired t test, p less than 0.01, n = 11), although the magnitude of this decrease varied considerably. The isoenzyme pattern before lavage was isomorphic, and this pattern was unchanged after whole lung lavage. This was in marked contrast to the LDH isoenzyme pattern observed in the lavage effluent, which showed a lower percent LDH1 and LDH2 and a higher percent LDH3, LDH4, and LDH5 when compared with the corresponding prelavage isoenzyme percentages for serum (unpaired t test, p less than 0.001). There was no correlation between the total serum LDH concentration and the total lavage LDH concentration. These data confirm that elevated serum LDH is a common finding in PAP. Furthermore, the LDH elevation found consistently in the alveolar fluid points to this as the source of the serum LDH.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchoalveolar Lavage Fluid↗
PubMed1991

Alveolar macrophage migration after lung transplantation.

Pulmonary infection is a major source of morbidity and mortality in recipients of lung allografts. The alveolar macrophage plays an important role in pulmonary host defense, and to fulfill this role it must have the ability to orient and migrate in the direction of a stimulus. Thus migratory activity was measured in cells recovered from lung transplant recipients by bronchoalveolar lavage. The primary patient group consisted of recipients who had no evidence of infection or rejection at the time of bronchoalveolar lavage. These patients were further subdivided into an early postoperative group (less than 6 wk posttransplant) and a late postoperative group (greater than 6 wk posttransplant). Other categories included patients with chronic rejection and a small group of patients with Pneumocystis carinii pneumonia. Alveolar macrophages recovered by bronchoalveolar lavage were assayed for migratory response to N-formylmethlonylphenylalanine and endotoxin-activated human serum. Stimulated migration of cells from healthy recipients obtained in the late postoperative course was similar to that of normal control subjects, but stimulated migration of cells from healthy recipients in the early postoperative period and those undergoing chronic rejection was greater than expected. Spontaneous migration was similar in all groups except those with P. carinii pneumonia, in whom it was greatly increased. We conclude that alveolar macrophage migration is not impaired in lung allograft recipients without apparent signs of infection or rejection and is in fact increased during periods of possible macrophage activation (shortly after transplantation and during chronic rejection).

Bronchoalveolar Lavage Fluid↗
PubMed1991

Three-dimensional histoculture: origins and applications in cancer research.

The ability to grow cells in monolayer culture has afforded investigators the opportunity to study many aspects of cancer cell biology under carefully controlled conditions. Nonetheless, an important factor that has often been overlooked is that cells in this configuration undergo a loss of structural integrity that may significantly alter their functional properties. Three-dimensional histoculture represents a useful alternative approach to monolayer culture because it preserves the native architecture of cells while still allowing ease of experimental manipulation. This review discusses the origins of three-dimensional cultures, the potential application of these cultures to assays of tumor cell metastasis and drug sensitivity, and the evidence from gene expression studies that these cultures may be more realistic tumor models than cell monolayers.

Animals↗
PubMed1990

Cloning and expression of a developmentally regulated protein that induces mitogenic and neurite outgrowth activity.

A heparin binding mitogenic protein isolated from bovine uterus shares NH2-terminal amino acid sequence with a protein isolated from newborn rat brain. The cDNA's of the bovine, human, and rat genes have been isolated and encode extraordinarily conserved proteins unrelated to known growth or neurotrophic factors, although identity of nearly 50 percent has been found with the predicted sequence of a retinoic acid induced transcript in differentiating mouse embryonal carcinoma cells. Lysates of COS-7 cells transiently expressing this protein were mitogenic for NRK cells and initiated neurite outgrowth from mixed cultures of embryonic rat brain cells. RNA transcripts encoding this protein were widely distributed in tissues and were developmentally regulated. This protein, previously designated as heparin binding growth factor (HBGF)-8, is now renamed pleiotrophin (PTN) to reflect its diverse activities. PTN may be the first member of a family of developmentally regulated cytokines.

Amino Acid Sequence↗
PubMed1990

The distinction of small cell and non-small cell lung cancer by growth in native-state histoculture.

Histological analysis remains the primary method of distinguishing between small cell (SCLC) and non-small cell lung cancer (NSCLC). This distinction has significant impact therapeutically because of their relative difference in chemoresponsiveness (J.D. Minna et al., Principles and Practice of Oncology, pp. 396-474, 1981). Yet for at least 10% of lung tumors, pathologists will disagree upon the classification (A.R. Feinstein et al., Am. Rev. Respir. Dis., 101: 671-684, 1970). Furthermore, current neuroendocrine markers lack specificity for SCLC although the presence of these markers may help predict chemosensitivity (S.L. Graziano et al., J. Clin. Oncol., 7: 1375-1376, 1989; S.B. Baylin, J. Clin. Oncol., 7: 1375-1376, 1989; C.L. Berger et al., J. Clin. Endocrinol. Metab., 53: 422-429, 1981; A.F. Gazdar et al., Cancer Res., 45: 2924-2930, 1985). In vitro growth characteristics may more accurately reflect biological properties of aggressiveness and susceptibility to chemotherapy. In this study, 3-dimensional gel-histoculture was used to retrospectively distinguish between NSCLC and SCLC. Tumor explants from 78 patients with NSCLC and 13 patients with SCLC were grown in gel-supported histocultures with an overall success rate of 92%. These 2 tumor types were distinguishable by their 3-dimensional in vitro tissue architecture. In addition, proliferation rates were measured by histological autoradiography after 4-day incorporation of [3H]dThd. The percentage of cells labeled in the most proliferatively active regions of the autoradiograms was termed the growth fraction index (A.F. Gazdar et al., Cancer Res., 45: 2924-2930, 1985; R.A. Vescio et al., Proc. Natl. Acad. Sci. U.S.A., 84: 5029-5033, 1987; R.M. Hoffman et al., Proc. Natl. Acad. Sci. U.S.A., 86: 2013-2017, 1989). The mean growth fraction index for pure small cell lung cancer was 79 +/- 10%, differing markedly from that of 35 +/- 19% for mixed small cell/large cell tumors, adenocarcinoma (38 +/- 16%), large cell undifferentiated carcinoma (40 +/- 18%), and squamous cell carcinoma (33 +/- 15%) (P less than 0.001 in each case). We therefore conclude that 3-dimensional gel-histoculture is a useful means of distinguishing pure SCLC from NSCLC, which may improve treatment decision making.

Carcinoma, Non-Small-Cell Lung↗
PubMed1990

Unbalanced transmethylation and the perturbation of the differentiated state leading to cancer.

It is proposed that the perturbation of the differentiated state in cancer is related to alterations in DNA methylation as well as to alterations in methylation of other cellular molecules, leading to an imbalance in global cellular methylation. It is hypothesized that the global imbalance in methylation is reflected in the enhanced levels of transmethylation seen in many cancer cell types as well as in a number of undermethylated molecules.

Animals↗
PubMed1990

Methylation of intact chromosomes by bacterial methylases in agarose plugs suitable for pulsed-field electrophoresis. Methylation of intact chromosomes in agarose by methylases.

Conditions were determined for the methylation of intact yeast chromosomes by EcoRI, HhaI, and MspI bacterial methylases using an endonuclease protection assay while the chromosomes were embedded in agarose plugs suitable for transverse-field electrophoresis. Parameters were also established for the methylation of human chromosomes by EcoRI methylase. Methylation of embedded chromosomes by EcoRI methylase required prewashes with EDTA. EcoRI, HhaI, and MspI methylases showed optimal activity when nonacetylated bovine serum albumin, high levels of S-adenosylmethionine, and high levels of methylase were used. The use of bacterial methylases for methylation of embedded chromosomes will allow investigators to normalize variations in cellular DNA methylation prior to restriction and create new and rare endonuclease recognition sites which will facilitate the detection of chromosomal alterations and deletions.

Chromosomes, Fungal↗
PubMed1990

Cancer biology for individualized therapy: correlation of growth fraction index in native-state histoculture with tumor grade and stage.

There is a need for individualization of all aspects of cancer therapy. Because of significant heterogeneity within a tumor class, there is a need to develop an in vitro test to accurately gauge tumor aggressiveness. Such a measurement would greatly aid treatment decision making. Current methodologies such as flow cytometry, which lacks unambiguous interpretation of cell-proliferative data, and determination of the thymidine-labeling index, which measures nucleotide uptake in a nonphysiological state, have not reproducibly attained this goal. We have developed an in vitro native-state three-dimensional gel-supported histoculture system that allows the growth of all human solid tumor types for relatively long time periods. The native-state system was used to identify the percent of cells capable of incorporating [3H]thymidine over a 4-day period, which we term the growth fraction index (GFI). We have compared the ability of cancer tissue to proliferate in native-state culture to the stage and histological grade of four major types of human carcinomas: breast, ovarian, colon, and lung. Eighty percent of tumor explants could be evaluated, even when sent from across the country. We have determined that the GFI correlates with tumor stage and grade for breast and ovarian carcinoma. In colon carcinoma, there is a trend toward higher GFIs in tumors of more advanced stage and grade. In non-small cell lung carcinomas, GFI, stage, and grade do not correlate. These results suggest the applicability of gel-supported three-dimensional native-state histoculture for prognostic purposes in patients with breast and ovarian cancers and demonstrate the clinical relevance of the native-state histoculture system.

Carcinoma, Non-Small-Cell Lung↗
PubMed1990

Experience with reduced-size liver transplantation.

Orthotopic liver transplantation with reduced-size liver transplants (RLT) has been proposed as a way of alleviating the limited availability of size-matched donor organs for pediatric recipients. The use of RLT should increase the pool of available donors and decrease the number of pediatric patients who die while awaiting a full-size hepatic graft. Between May 1988 and April 1989, 15 RLT were placed in 12 patients. Twelve were left lobe and three were extended right lobe grafts. The mean donor to recipient ratio was 9.0:1.0 (range of 3.3:1.0 to 19.9:1.0). Graft complications occurred in four RLT, and extrahepatic complications occurred in five patients. Preservation of grafts with University of Wisconsin solution was used in all instances, with a mean preservation time of 14.1 hours (range of 8.5 to 19.5 hours). Retransplantation with RLT was successful in three of four patients. The actual patient survival rate was 83 per cent after a mean follow-up interval of 6.7 months (range of one to 11 months). Our experience indicates that patient survival with RLT is comparable with full-size grafting and should be offered as an acceptable method of therapy for end-stage liver disease in pediatric patients. The application of RLT techniques in a more elective setting may yield further improvements in patient survival.

Child↗
PubMed1989

A novel 17 kD heparin-binding growth factor (HBGF-8) in bovine uterus: purification and N-terminal amino acid sequence.

We have purified to near homogeneity a novel 17 kD growth factor from bovine uterus which we designated heparin-binding growth factor-8 (HBGF-8). The growth factor binds tightly to cation exchange resins and to Heparin-Sepharose and is stable to acetone precipitation and labile in acid. Based upon total activity in acetone extracts of bovine uterus stimulating 3H-thymidine incorporation into DNA of serum-starved NIH 313 cells, a 6940 fold purification was achieved with an overall yield of HBGF-8 activity of 0.4%, using extraction of acetone powders and chromatographic separations at neutral pH. Approximately 18 micrograms protein was obtained from 1.2 kg wet weight of tissue. HBGF-8 was clearly separated from 17.5 kD bovine uterus basic fibroblast growth factor (bFGF) by purification and its N-terminal amino acid sequence analyzed. A polypeptide with a unique 25 N-terminal amino acid sequence was found. HBGF-8 was as active as acidic fibroblast growth factor (aFGF) and slightly less active than bFGF in the mouse NIH 3T3 fibroblast mitogenic assay system with an intrinsic specific activity of 5000 dpm/ng under standard assay conditions.

Amino Acid Sequence↗
PubMed1989

Minimal antiproliferative effect of recombinant müllerian inhibiting substance on gynecological tumor cell lines and tumor explants.

Múllerian Inhibiting Substance (MIS) is a testicular hormone that promotes involution of the Múllerian duct during embryogenesis. The Múllerian duct gives rise to adult female reproductive ducts including the fallopian tubes, uterus, and upper vagina. Thus, testicular MIS ensures the regression of female sex organ primordia. Partially purified bovine MIS was reported to inhibit proliferation of tumor cells derived from human gynecological cancers. These observations suggest that MIS might be an effective anticancer agent for some human tumors. Recombinant human MIS (rHu-MIS) has recently become available. To assess the antiproliferative activity of rHu-MIS, we examined its effects on 11 ovarian, six endometrial, and two nongynecological human tumor cell lines. rHu-MIS had no effect on proliferation of these cell lines in five independent assays. Forty-three primary human tumor explants were also examined in human tumor colony forming assays, gel-supported primary culture assays, and subrenal capsule assays. rHu-MIS significantly inhibited the growth of five of these tumors including four ovarian and one small cell lung cancer explant. The four ovarian cancer responses include three of 13 (23%) explants tested in human tumor colony-forming assays and one of eight (12.5%) explants tested in gel-supported primary culture assays. We conclude that rHu-MIS may have antiproliferative activity against some human ovarian cancers.

Animals↗
PubMed1989

Separation and identification of two phosphatidylinositol 4-kinase activities in bovine uterus.

Growth factor-activated second messenger pathways are mediated in part via breakdown products of phosphoinositides. We have separated two phosphatidylinositol (PtdIns) 4-Kinases from bovine uteri which appear to be regulated independently. The predominant type II enzyme previously was purified to apparent homogeneity; the type I enzyme has been purified approximately 1000 fold (specific activity, approximately 30 nmoles/mg/min). The type I and type II enzymes differ sharply in apparent Km for ATP and response to divalent cations. In contrast to type II enzyme, type I PtdIns kinase was resistant to inhibition by adenosine, inhibited by increasing concentrations of Triton X-100, and less stable to storage than type II enzyme at pH values below 6.5 and above 8.5. Type I PtdIns 4-kinase has an apparent molecular mass of approximately 200 kD and type II enzyme of approximately 80 kD. Using both enzymatic and chemical criteria, both enzymes specifically phosphorylated the fourth hydroxyl group of PtdIns. The results thus establish the presence of two distinct and separate enzymes catalyzing PtdIns 4-kinase activity with different physical, kinetic, and regulatory properties, suggesting an important site for the regulation of second messenger signals transducing the responsiveness of cells to growth factors.

1-Phosphatidylinositol 4-Kinase↗
PubMed1989

A general native-state method for determination of proliferation capacity of human normal and tumor tissues in vitro.

An important need in cancer research and treatment is a physiological means in vitro by which to assess the proliferation capacity of human tumors and corresponding normal tissue for comparison. We have recently developed a native-state, three-dimensional, gel-supported primary culture system that allows every type of human cancer to grow in vitro at more than 90% frequency, with maintenance of tissue architecture, tumor-stromal interaction, and differentiated functions. Here we demonstrate that the native-state culture system allows proliferation indices to be determined for all solid cancer types explanted directly from surgery into long-term culture. Normal tissues also proliferate readily in this system. The degree of resolution of measurement of cell proliferation by histological autoradiography within the cultured tissues is greatly enhanced with the use of epi-illumination polarization microscopy. The histological status of the cultured tissues can be assessed simultaneously with the proliferation status. Carcinomas generally have areas of high epithelial proliferation with quiescent stromal cells. Sarcomas have high proliferation of cells of mesenchymal organ. Normal tissues can also proliferate at high rates. An image analysis system has been developed to automate proliferation determination. The high-resolution physiological means described here to measure the proliferation capacity of tissues will be important in further understanding of the deregulation of cell proliferation in cancer as well as in cancer prognosis and treatment.

Breast Neoplasms↗
PubMed1989

Improvement in alveolar macrophage migration after therapeutic whole lung lavage in pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by the accumulation of lipoproteinaceous material in the alveolar space. Alveolar macrophages (AM) in this disease have been noted in the past to have abnormally decreased function. It is not known whether these abnormalities are reversible with treatment of the disease. In this study, the effect of therapeutic whole lung lavage (WLL) on AM migration in four patients with PAP was determined. Standard segmental bronchoalveolar lavage (BAL) was performed 1 day before and 6 days after WLL. AM recovered by BAL were assayed for migratory response to N-formyl-methionyl phenylalanine (FMP) and endotoxin-activated human serum (EAHS). As expected, migration toward both stimuli was decreased before WLL compared to a group of normal controls. After WLL, AM migration toward both stimuli was not only greater than before the WLL but also was greater than normal. In one patient, serial BAL over a period of 18 months showed a marked decline in AM migration coincident with a clinical relapse of the disease. Thus, the defect in AM function found in PAP is reversible with WLL but can recur if clinical remission is not sustained.

Cell Migration Inhibition↗