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Biomedical subjects

D S Miller

Publications and source records attributed to D S Miller.

At least 109 records · Page 6Linked to original sources
PubMed1994

Lipopolysaccharide (LPS)-binding protein accelerates the binding of LPS to CD14.

CD14 is a 55-kD protein found as a glycosylphosphatidylinositol (GPI)-anchored protein on the surface of monocytes, macrophages, and polymorphonuclear leukocytes, and as a soluble protein in the blood. Both forms of CD14 participate in the serum-dependent responses of cells to bacterial lipopolysaccharide (LPS). While CD14 has been described as a receptor for complexes of LPS with LPS-binding protein (LBP), there has been no direct evidence showing whether a ternary complex of LPS, LBP, and CD14 is formed, or whether CD14 binds LPS directly. Using nondenaturing polyacrylamide gel electrophoresis (native PAGE), we show that recombinant soluble CD14 (rsCD14) binds LPS in the absence of LBP or other proteins. Binding of LPS to CD14 is stable and of low stoichiometry (one or two molecules of LPS per rsCD14). Recombinant LBP (rLBP) does not form detectable ternary complexes with rsCD14 and LPS, but it does accelerate the binding of LPS to rsCD14. rLBP facilitates the interaction of LPS with rsCD14 at substoichiometric concentrations, suggesting that LBP functions catalytically, as a lipid transfer protein. Complexes of LPS and rsCD14 formed in the absence of LBP or other serum proteins strongly stimulate integrin function on PMN and expression of E-selectin on endothelial cells, demonstrating that LBP is not necessary for CD14-dependent stimulation of cells. These results suggest that CD14 acts as a soluble and cell surface receptor for LPS, and that LBP may function primarily to accelerate the binding of LPS to CD14.

Acute-Phase Proteins↗
PubMed1994

Potential applications of intracardiac echocardiography in interventional electrophysiology.

The growth of interventional electrophysiology in recent years has placed a greater demand on imaging guidance. Currently available imaging modalities to guide interventions, while useful, have significant limitations. Intracardiac echocardiography has the potential to improve on these limitations and evolve into a modality that could provide imaging guidance, aid in the prevention or instant identification of complications, help identify and quantify ablative lesions, and contribute toward visualization of normal and abnormal conduction pathways. Ongoing developments in catheter design in the form of lower frequency, smaller size, and preshaped catheters should enhance the role of intracardiac echocardiography in interventional electrophysiology. There is the potential to combine the imaging and ablative capabilities of intracardiac ultrasonography to make for an imaging and therapeutic tool.

Cardiac Catheterization↗
PubMed1994

CNS-directed case management. Cost and quality in harmony.

Preserving the integrity of high quality care in a financially restricted environment is the primary challenge facing healthcare providers. The critical question is which delivery system will use limited resources most efficiently without jeopardizing quality of care? Case management has been identified as a solution that offers the most promise. The case management model at Sioux Valley Hospital was developed to deal proactively with resource-intensive patients with chronic illnesses who have frequent admissions and who create financial risk for the hospital. The authors describe the fiscal and clinical outcomes of these select patients.

Adolescent↗
PubMed1994

Confocal microscopic analysis of fluorescein compartmentation within crab urinary bladder cells.

Fluorescein (FL), a fluorescent organic anion, is compartmentalized in cells of organic anion-secreting epithelia, e.g., OK cells, teleost proximal tubule, and crab (Cancer borealis) urinary bladder, a proximal tubule analogue. To further examine the processes involved, FL uptake and distribution were studied in C. borealis urinary bladder cells using epifluorescence and laser confocal microscopy combined with video-image analysis. Intracellular FL was about evenly split between diffuse and punctate compartments after in vitro or in vivo loading. Treatments that affected FL transport into cells (incubation with p-aminohippuric acid or glutarate) altered the FL content of both compartments. However, nocodazole, a microtubule inhibitor, did not affect diffuse FL but significantly reduced punctate FL. Finally, confocal analysis indicated that individual sites of punctate FL accumulation moved in the secretory direction at 0.83 micron/min. Nocodazole nearly abolished this movement and significantly reduced transepithelial organic anion secretion. Thus, in crab urinary bladder, a substantial fraction of total cellular FL is sequestered in vesicles, and these vesicles move in the secretory direction, by a microtubule-dependent process.

Animals↗
PubMed1994

Nocodazole inhibition of organic anion secretion in teleost renal proximal tubules.

The impact of the microtubule-disrupting drug nocodazole on renal tubular secretion of organic anions was examined in vitro using proximal tubular masses from teleost fish. Nocodazole reversibly inhibited 20-30% of the tubular accumulation of two model organic anions, p-aminohippurate and fluorescein (FL), by winter flounder tubular masses. However, the drug had no effect on the initial rate of organic anion uptake. Thus it did not reduce transport into the cells at the basolateral membrane, either directly by affecting basolateral organic anion transport proteins or indirectly by altering metabolism or ion gradients. Instead, epifluorescence video microscopy and digital image analysis of killifish tubules showed that nocodazole greatly reduced luminal accumulation of FL and had a smaller effect on cellular dye accumulation. Luminal FL accumulation returned to control levels when tubules were incubated in drug-free medium. Confocal fluorescence microscopy confirmed the marked reduction in luminal FL concentration and demonstrated that intracellular punctate FL accumulation was also markedly reduced. Finally, immunohistochemistry with an anti-tubulin antibody showed that the concentrations of nocodazole used in the above experiments reversibly disrupted microtubules within renal epithelial cells. These data indicate that a component of organic anion secretion in teleost proximal tubule is dependent on an intact microtubular network.

Animals↗
PubMed1994

ATP-dependent transport of tetraethylammonium by endosomes isolated from rat renal cortex.

During renal organic cation secretion by some species, intracellular concentrations greatly exceed the 10- to 15-fold ratio predicted by the potential-driven mechanism thought to mediate their basolateral uptake. Free cytoplasmic organic cation concentrations within the tubular cells might be decreased through sequestration within intracellular organelles. The data reported here show that endosomal vesicles isolated from rat renal cortex take up tetraethylammonium (TEA) by an ATP-dependent mechanism. Addition of 0.2-5 mM ATP to the medium stimulated uptake 5- to 10-fold at 5 min and 20-fold at 60 min. More than 80% of the ATP-dependent uptake was associated with an osmotically active space. The nonhydrolyzable ATP analogue, adenosine 5'-O-(3-thiotriphosphate), did not stimulate TEA uptake. Mg2+ and Cl- were required for stimulation. Uptake was inhibited by several organic cations, including TEA itself. Uptake was also inhibited by inhibitors of intravesicular acidification, e.g., monensin and N-ethylmaleimide. Furthermore, the ATP requirement could be bypassed by establishing a pH gradient (inside acidic). These data show that endosomal TEA accumulation is mediated by proton/TEA exchange and is driven by the pH gradient maintained by H(+)-adenosinetriphosphatase. This potent sequestration mechanism may play an important role in organic cation secretion.

Adenosine Triphosphate↗
PubMed1994

Differences in the procurement of organs and tissues by health care professionals.

BACKGROUND: The act of donating organs is familiar to most health care professionals (HCPs). However, the process of tissue and cornea donation is not nearly as well known. Most studies of the donation process have neglected the issue of tissue and cornea donation. This study offers some preliminary data concerning the differences between organ and tissue and cornea donation processes. As well, this is one of the first studies to report an eligibility rate for tissues among hospital deaths. METHODS: During a 5-month period in 1989, the charts of all patients (n = 233) who died in the study hospital were reviewed on a weekly basis to establish eligibility to donate organs, tissues and corneas. A case series of 50 eligible patients cases was selected for in-depth interviews. Cases were defined as those patients who were eligible to donate tissues or organs. The patient's attending physician, house officer, and primary nurse were interviewed using an open-ended interview format. These audiotaped interviews focused on the events surrounding the patient's death, focusing on the issue of donation. We also collected information concerning HCP knowledge of the medical criteria for donation and their attitudes toward donation. Consent was obtained from all HCPs before beginning the interview process. RESULTS: Of the 233 deaths, 4.3% were eligible to donate organs, 11.2% were eligible to donate tissues, and 18.9% were eligible to donate corneas. On the basis of our interview data we found that all eligible organ donors were identified and their families asked by at least one member of the patient's health care team to consider donation. HCPs were less successful identifying tissue patients: 30 of the 41 tissue donors (73.2%) were identified and only 65.9% of donor families were asked to donate. Rates of consent to donation were lower than might be expected based on public opinion polls. 33.3% of families consented to organ donation while only 29.6% consented to donate tissue and cornea. CONCLUSION: HCPs performed less efficiently in terms of the procurement process for tissues and corneas as compared to organs. They were also less knowledgeable about the donation criteria for tissues and corneas than organs. They generally exhibited more positive attitudes about corneal donation. More education of HCPs is necessary before we can optimally procure tissues for transplantation.

Aged↗
PubMed1993

Mortality rates in displaced and resident populations of central Somalia during 1992 famine.

Famine and civil war have resulted in high mortality rates and large population displacements in Somalia. To assess mortality rates and risk factors for mortality, we carried out surveys in the central Somali towns of Afgoi and Baidoa in November and December, 1992. In Baidoa we surveyed displaced persons living in camps; the average daily crude mortality rate was 16.8 (95% CI 14.6-19.1) per 10,000 population during the 232 days before the survey. An estimated 74% of children under 5 years living in displaced persons camps died during this period. In Afgoi, where both displaced and resident populations were surveyed, the crude mortality rate was 4.7 (3.9-5.5) deaths per 10,000 per day. Although mortality rates for all displaced persons were high, people living in temporary camps were at highest risk of death. As in other famine-related disasters, preventable infectious diseases such as measles and diarrhoea were the primary causes of death in both towns. These mortality rates are among the highest documented for a civilian population over a long period. Community-based public health interventions to prevent and control common infectious diseases are needed to reduce these exceptionally high mortality rates in Somalia.

Adolescent↗
PubMed1993

DNA flow cytometric analysis of clinical stage I endometrial carcinomas with lymph node metastases.

Twenty-one (8%) of 264 consecutive evaluable patients with clinical stage 1 endometrial carcinoma had histologic evidence of pelvic and/or para-aortic lymph node metastases. DNA flow cytometry was performed on both the primary tumor and nodal metastasis. Seventeen of 21 sets could be analyzed. Overall, 11 (65%) of the primary carcinomas were aneuploid. Nine of 17 (53%) had consistent ploidy patterns when the primary tumor and lymphatic metastasis were compared. The remaining 8 (47%) had aneuploid primaries with diploid nodal metastases. Five (83%) of the 6 patients with diploid primary tumors were alive without evidence of disease compared to 3 of 11 (27%) patients with aneuploid tumors (P < 0.05). Other predictors of disease outcome included tumor histology, lymph vascular space invasion, and depth of myometrial invasion. Ploidy status of the lymphatic metastasis was not important in terms of overall survival. All 8 patients with para-aortic nodal metastases had aneuploid primary carcinomas compared to 4 (44%) of 9 patients with pelvic node involvement only (P < 0.01). Mean survival was 31 months for patients with para-aortic node metastases compared to 51 months for patients with only pelvic node metastases. Comparison of survival curves among these two groups demonstrated a significant survival advantage in patients with regional nodal metastases (P = 0.032). S-phase fraction of both the primary tumor and lymphatic metastasis did not correlate with survival or predict disease outcome. DNA index of the primary tumor, as a continuous variable, was inversely proportional to survival, demonstrating poorer survivorship with incremental increases of DI. Ploidy status of the lymph node metastasis was an inconsistent reflection of the primary tumor's expression and behavior and, therefore, little additional information was gained by knowledge of the lymphatic ploidy status.

Adult↗
PubMed1993

Intracellular compartmentation of organic anions within renal cells.

Epifluorescence microscopy and video-image analysis were used to measure the distribution of the monovalent organic anion fluorescein (FL) within the cells of three organic anion-secreting renal epithelia: crab urinary bladder (a proximal tubule analogue), opossum kidney (OK) cells in culture, and intact teleost proximal tubules. In all three preparations the intracellular FL distribution was nonuniform. Two distinct intracellular compartments were detected, one being diffuse and cytoplasmic and the other punctate. With low FL concentrations in the medium (1 microM and below) dye accumulation in the punctate compartment exceeded that of the cytoplasm. In crab bladder epithelium FL uptake into both compartments was inhibited by external probenecid, p-aminohippurate (PAH), and LiCl and stimulated by 10-50 microM external glutarate, suggesting that the punctate compartment loaded by a two-step mechanism: transport into the cytoplasm at the basolateral membrane, followed by accumulation at specific intracellular sites. Experiments in which FL was microinjected into OK cells directly demonstrated movement of FL from the cytoplasmic to the punctate compartment. Accumulation in the latter was specific, i.e., inhibitable by coinjected PAH and probenecid, and energy dependent. Together, these findings indicate that during secretion organic anions are sequestered within renal cells. The role of sequestration in overall transport remains to be determined.

Animals↗
PubMed1993

Flow cytometric evaluation of early invasive cervical cancer.

OBJECTIVE: To define the role of flow cytometry as a prognostic indicator in early cancers of the uterine cervix. METHODS: Flow cytometry was used to determine ploidy, DNA index, and S-phase fraction on 141 samples from the tumors of 53 women with stage IB cancers of the cervix treated by radical hysterectomy and pelvic lymphadenectomy as primary therapy. Multiple samples of the same tumor were analyzable for 47 (89%) of the subjects. One-way analysis of variance for the multiple samples was used to compare the heterogeneity of flow cytometry data, both within each tumor and between patients. Flow cytometry results, as well as previously described clinical and pathologic prognostic factors, were correlated to recurrence and survival using Cox regression hazard ratios and Kaplan-Meier estimates. RESULTS: We found DNA aneuploidy in 25 (47%) of the cancers, with a mean (+/- standard error) DNA index of 1.52 +/- 0.07. The mean S-phase fraction was 7.6 +/- 0.4% for diploid tumors and 9.2 +/- 0.4% for aneuploid tumors. The cancers from 24 women (45%) were homogeneously diploid, 18 (34%) were consistently aneuploid, and five (9%) had mixed diploid/aneuploid samples. Analysis of variance of the multiple samples for each woman revealed a greater standard deviation (SD) between patients than within any individual tumor for both DNA index (ratio of between SD to within SD 2.1; P < .0001) and S-phase fraction (ratio 1.6; P < .0001). Of the previously described clinical and pathologic prognostic factors, only depth of invasion, expressed as either percent of cervical wall thickness or as thirds, was correlated with recurrence or survival. Neither the DNA index nor S-phase fraction correlated significantly with recurrence or survival. CONCLUSIONS: These results suggest that alterations in the DNA content or proliferative activity of early invasive cancers of the uterine cervix do not reflect biologic behavior in terms of recurrence or survival, and that this behavior is not due to tumor heterogeneity.

Adenocarcinoma↗
PubMed1992

Soluble CD14 participates in the response of cells to lipopolysaccharide.

CD14 is a 55-kD protein found both as a glycosylphosphatidyl inositol-linked protein on the surface of mononuclear phagocytes and as a soluble protein in the blood. CD14 on the cell membrane (mCD14) has been shown to serve as a receptor for complexes of lipopolysaccharide (LPS) with LPS binding protein, but a function for soluble CD14 (sCD14) has not been described. Here we show that sCD14 enables responses to LPS by cells that do not express CD14. We have examined induction of endothelial-leukocyte adhesion molecule 1 expression by human umbilical vein endothelial cells, interleukin 6 secretion by U373 astrocytoma cells, and cytotoxicity of bovine endothelial cells. None of these cell types express mCD14, yet all respond to LPS in a serum-dependent fashion, and all responses are completely blocked by anti-CD14 antibodies. Immunodepletion of sCD14 from serum prevents responses to LPS, and the responses are restored by addition of sCD14. These studies suggest that a surface anchor is not needed for the function of CD14 and further imply that sCD14 must bind to additional proteins on the cell surface to associate with the cell and transduce a signal. They also indicate that sCD14 may have an important role in potentiating responses to LPS in cells lacking mCD14.

Animals↗
PubMed1992

Functional expression of renal organic anion transport in Xenopus laevis oocytes.

Secretion of organic anions by the kidney plays a critical role in the elimination of toxic agents from the body. Recent findings in isolated membranes and intact tissue have demonstrated the participation of multiple transport proteins in this process. As a first step toward molecular characterization of these proteins through expression cloning, the studies reported below demonstrate functional expression of both fumarate- and lithium-sensitive glutarate and probenecid-sensitive p-aminohippurate transport in Xenopus oocytes injected with rat kidney poly(A)+ RNA. Maximal increase in substrate uptake over buffer-injected controls was reached by 5 days after mRNA injection. Expression of size-fractionated mRNA indicated that the active species with respect to both transport activities were in the range of 1.8 to 3.5 kb.

Animals↗
PubMed1992

Septin: a factor in plasma that opsonizes lipopolysaccharide-bearing particles for recognition by CD14 on phagocytes.

We have previously reported that lipopolysaccharide (LPS) binding protein (LBP) opsonizes endotoxin (LPS) for recognition by CD14 on phagocytes. Here we show that normal human plasma contains high titers of an activity that also binds LPS (Re, 595) and mediates recognition by CD14. Opsonization of LPS-coated particles with plasma enables the particles to be bound by phagocytes. Further, opsonization with plasma also enables subnanogram-per-milliliter concentrations of LPS to induce dramatic alterations in the function of leukocyte integrins on polymorphonuclear leukocytes and to induce secretion of tumor necrosis factor by monocytes, suggesting that opsonization by factors in plasma may be important in responses of cells to endotoxin. The opsonic activity in plasma appears distinct from LBP since it is not blocked by neutralizing antibodies against LBP. Surprisingly, the opsonic activity of plasma is not present in a single protein species, but at least two species must be combined to observe activity. Further, the opsonic activity of plasma for LPS is blocked by addition of protease inhibitors, suggesting that proteolytic activity or activities are required for opsonization. These properties are suggestive of the action of a protease cascade, but opsonic activity of plasma is not affected by blockade or depletion of either the complement or clotting cascades. We propose the name "septin" to describe this novel LPS-opsonizing activity in plasma.

Acute-Phase Proteins↗
PubMed1992

Critical reassessment of second-look exploratory laparotomy for epithelial ovarian carcinoma. Minimal diagnostic and therapeutic value in patients with persistent cancer.

From 1979 to 1984, 88 women with epithelial ovarian cancer were treated with surgery and chemotherapy, achieved a clinical complete response, and then had "second-look" exploratory laparotomy to assess the pathologic status of their disease. Persistent cancer was found in 50 (57%) patients: 34 of 50 (68%) had gross tumor, which was larger than 2 cm in 12 (24%) and smaller than 2 cm in 22 (44%), and 16 (32%) had microscopic disease. Salvage therapy was as follows for these patients: whole abdominal irradiation, 29 (58%); chemotherapy, 17 (34%); intraperitoneal chromic phosphate, 1 (2%); and no further therapy, 3 (6%). With a follow-up time of 4 to 8 years, 7 (14%) patients are alive without evidence of cancer, 7 (14%) are alive with disease, 35 (70%) are dead of disease, and 1 (2%) has died of treatment complications. At 5 years, the relapse-free rate was 18% and the survival rate was 25%. Seventy-two parameters of suspected prognostic significance and 64 potential sites of tumor involvement were correlated with survival in a univariate analysis. The factors favorably affecting survival included the following: lower grade; microscopic tumor versus gross disease at second-look laparotomy; removal of the uterus; removal of the omentum; pelvic and paraaortic lymph node biopsy; negative results of a right diaphragm biopsy; and radiation therapy at Stanford University Medical Center, Stanford, California. There was no survival advantage for whole abdomen irradiation compared with chemotherapy or for the patients who had their disease successfully debulked at second-look laparotomy. The above factors and others were evaluated by multivariate regression. The best model (P = 0.000004) for predicting survival included largest tumor mass (P = 0.0002), operative blood loss (P = 0.002), perioperative blood transfusion (P = 0.003), and grade (P = 0.004). The detection of persistent ovarian cancer by second-look exploratory laparotomy should identify a subgroup of patients whose conditions can be salvaged by a second-line therapy. Unfortunately, that subgroup is small (8%) and an effective salvage therapy remains to be identified.

Combined Modality Therapy↗
PubMed1992

A phase II trial of leuprolide acetate in patients with advanced epithelial ovarian carcinoma. A Gynecologic Oncology Group study.

Twenty-five evaluable patients with advanced or recurrent epithelial ovarian carcinoma that was no longer controllable with surgery, radiation therapy, and/or chemotherapy were treated with leuprolide acetate, a gonadotropin-releasing hormone agonist, 1 mg subcutaneously daily. One partial response (4%) was observed among the 25 patients. The upper 95% confidence bound of the response rate is 17.6%. Fifteen patients (60%) exhibited stable disease for at least 8 weeks, and 9 patients (36%) developed progressive cancer while receiving treatment. The regimen was well tolerated with no patient experiencing life-threatening toxicity. Mild toxicities included leukopenia in 2 patients (8%), thrombocytopenia in 2 patients (8%), gastrointestinal toxicity in 5 patients (20%), anemia in 4 patients (16%), hot flashes in 1 patient (4%), and facial swelling in 1 patient (4%). Thus, leuprolide acetate was well tolerated but has insignificant activity in treating patients with chemotherapy-refractory ovarian adenocarcinoma.

Adenocarcinoma↗
PubMed1992

Etoposide, methotrexate, actinomycin D, cyclophosphamide, and vincristine for the treatment of metastatic, high-risk gestational trophoblastic disease.

OBJECTIVE: To evaluate the efficacy and toxicity of a regimen of etoposide, methotrexate, actinomycin D, cyclophosphamide, and vincristine in patients with metastatic, high-risk gestational trophoblastic tumors. METHODS: Twelve women with metastatic gestational choriocarcinoma received 64 treatment cycles. All met the National Cancer Institute criteria for high-risk gestational trophoblastic tumors. Response was evaluated by monitoring serial serum beta-hCG levels. Toxicity was recorded using standard World Health Organization criteria. RESULTS: There was no life-threatening toxicity. Neutropenia necessitating a 1-week delay of treatment occurred with only eight treatment cycles (12.5%) and deferral of vincristine and cyclophosphamide with three cycles. Anemia requiring transfusion complicated only two cycles. Peripheral neuropathy in two patients was treated by discontinuing vincristine. Other toxicities included nausea and vomiting, diarrhea, stomatitis, alopecia, conjunctivitis, thrombocytopenia, and fever. Ten of the 12 subjects experienced a complete response. Two had partial responses and one with an initial complete response had relapse 4 months after completing therapy; all three were successfully salvaged with cisplatin-based chemotherapy. Overall survival was 100%, and all 12 patients are disease-free with a median follow-up of 26 months. CONCLUSIONS: Chemotherapy with etoposide, methotrexate, actinomycin D, cyclophosphamide, and vincristine is well tolerated and highly effective for metastatic, high-risk gestational trophoblastic disease.

Adult↗