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Biomedical subjects

A Stein

Publications and source records attributed to A Stein.

At least 91 records · Page 5Linked to original sources
PubMed2000

Kidney function after radical nephrectomy: assessment by quantitative SPECT of 99mTc-DMSA uptake by the kidneys.

UNLABELLED: To determine the function of the remaining contralateral kidney after the removal of a functioning kidney, 30 consecutive patients (18 men, 12 women; average age, 67 y; age range, 34-87 y) who were undergoing unilateral radical nephrectomy were evaluated by sequential quantitative 99mTc-dimercaptosuccinic acid (DMSA) SPECT (QDMSA) studies. METHODS: The 30 patients were undergoing radical nephrectomy for renal tumors. The first study was done before surgery. Follow-up studies were performed 2-23 mo after surgery. Clinical evaluations and determinations of serum creatinine level were performed at the same time as the QDMSA studies. RESULTS: The relative contribution of the resected kidneys to the global renal function before surgery was 43.2% +/- 7.3%. After surgery the uptake of the remaining kidney increased from 13.4% +/- 4.0% to 18.3% +/- 5.8% (t = 5.7; P = 0.0000). The relative function of the remaining kidney increased from 56.8% +/- 7.1% to 79.1% +/- 23.6% (t = 4.9; P < 0.0001) of the global renal function before nephrectomy. Increases in the renal volume (from 211 +/- 62 cm3 to 229 +/- 68 cm3; t = 4.5; P = 0.0001) and in the percentage injected dose per cubic centimeter (%ID/cm3) of the remaining kidney (from 0.066 +/- 0.02 % ID/cm3 to 0.085 +/- 0.03 %ID/cm3; t = 4.6; P = 0.0001) were associated with this change. Nine patients had 2 follow-up studies performed 3-4 mo after surgery and 12-14 mo after surgery. The volume of the remaining kidney (209.22 +/- 46.20 cm3 versus 217.88 +/- 58.85 cm3; t = 0.962; P = 0.364), the %ID/cm3 (0.09 +/- 0.016 %ID/cm3 versus 0.093 +/- 0.025 %ID/cm3; t = 0.362; P = 0.726), and the percentage uptake (19.26% +/- 4.45% versus 20.11% +/- 7.01%) did not change significantly between these 2 QDMSA studies. CONCLUSION: The results of this study suggest that adaptive changes causing hyperfunction of the remaining kidney may occur after nephrectomy of a functioning kidney in adults. These changes occur soon after surgery, persist for at least 1 y, and are evident on QDMSA studies.

Adaptation, Physiological↗
PubMed2000

Amprenavir in combination with lamivudine and zidovudine versus lamivudine and zidovudine alone in HIV-1-infected antiretroviral-naive adults. Amprenavir PROAB3001 International Study Team.

OBJECTIVES: To compare the antiviral activity and safety of a new protease inhibitor, amprenavir (141W94) in combination with lamivudine and zidovudine, versus lamivudine and zidovudine alone in HIV-1 infected, antiretroviral-naive subjects. DESIGN: Subjects (n=232) with a CD4 T cell count of > or =200 cells/mm3, plasma HIV-1 RNA levels of > or =10000 copies/ml, and < or =4 weeks of prior nucleoside antiretroviral therapy, were stratified according to baseline plasma HIV-1 RNA level (10000-30000; 30000-100000; or >100000 copies/ml). Subjects received double-blind treatment with either 1200 mg amprenavir twice daily in combination with lamivudine (150 mg twice daily) and zidovudine (300 mg twice daily) (amprenavir/lamivudine/zidovudine) or matched placebo, lamivudine and zidovudine for 16 weeks. Thereafter, subjects with confirmed plasma HIV-1 RNA levels of > or =400 copies/ml could add open-label amprenavir or switch to other antiretrovirals and continue treatment for up to a minimum of 48 weeks. The primary endpoint of the study was defined as the proportion of subjects with plasma HIV-1 RNA of <400 copies/ml at 48 weeks. RESULTS: At 48 weeks, a significantly greater proportion of amprenavir/lamivudine/zidovudine subjects had plasma HIV-1 RNA levels <400 copies/ml than lamivudine/ zidovudine subjects in the overall population: 41 versus 3% (intent-to-treat missing equals failure analysis) (P<0.001); 93 versus 42% (as-treated analysis) (P<0.001); and within each of the three randomization strata (P<0.001). Subjects on amprenavir/lamivudine/zidovudine experienced longer time to event (permanent discontinuation of randomized therapy or viral rebound) than those on lamivudine/zidovudine (median of 33 versus 13 weeks; P<0.001). A significantly greater incidence of drug-related nausea, vomiting, rash and oral/perioral paresthesia was observed with amprenavir/lamivudine/zidovudine than with lamivudine/zidovudine. CONCLUSIONS: Amprenavir, in combination with lamivudine and zidovudine, has potent and durable antiviral activity in antiretroviral-naive subjects over 48 weeks. Amprenavir was safe and generally well tolerated.

Adolescent↗
PubMed1999

A phase II safety and efficacy study of amprenavir in combination with zidovudine and lamivudine in HIV-infected patients with limited antiretroviral experience. Amprenavir PROAB2002 Study Team.

OBJECTIVE: To determine the safety and efficacy of amprenavir (APV) in combination with lamivudine (3TC) and zidovudine (ZDV). DESIGN: Multicenter, randomized, partially blinded trial. SETTING: Nine study sites in the United States and Europe. PATIENTS: A group of 84 HIV-infected subjects with no prior 3TC or protease inhibitor therapy experience, CD4 cell count > or = 150 x 10(6) cells/l, and plasma HIV RNA > 10000 copies/ml. INTERVENTIONS: 3TC/ZDV with one of three doses of APV (900, 1050, or 1200 mg) versus 3TC/ZDV with 1050 mg placebo. All medications were dosed twice daily. The 1050 mg placebo and the APV 1050 mg dose were administered blinded. After 12 weeks, APV 1050 mg was substituted for 1050 mg placebo in the control group and the blind was maintained. MAIN OUTCOME MEASURES: Reduction in plasma HIV RNA from baseline; proportion of subjects with plasma HIV RNA < 400 copies/ml; and an increase in CD4 cell count from baseline. RESULTS: During the initial 12-week study period, APV/3TC/ZDV-treated subjects had greater viral suppression than the group receiving two nucleosides. By 48 weeks, 89% of subjects in the group taking the highest APV dose (1200 mg) had plasma HIV RNA < 400 copies/ml while 42% of the 900 mg group and 60% of the 3TC/ZDV group (1050 mg APV added at week 12) had plasma HIV RNA < 400 copies/ml using an as-treated analysis. By 60 weeks, 86% of subjects in the APV 1200 mg group had plasma HIV RNA < 400 copies/ml in the as-treated analysis, while 25% (900 mg), 43% (1050 mg), and 20% (1200 mg) of subjects had viral load <400 copies/ml in a strict intent-to-treat analysis owing to treatment discontinuations. Median CD4 cell count increases at week 60 were highest for the three treatment groups who received APV throughout the study, by intent-to-treat and as-treated analyses. The most common adverse events considered to be possibly drug related were nausea, rash, oral paresthesia, diarrhea, and fatigue. CONCLUSIONS: Treatment with APV, dosed at 1200 mg twice daily in combination with 3TC/ZDV, resulted in sustained viral suppression. This combination represents a potent alternative initial antiretroviral regimen for protease inhibitor-naive individuals.

Adult↗
PubMed1999

Telomerase activity in patients with transitional cell carcinoma: a preliminary study.

BACKGROUND: Telomerase activity is not detectable in normal cells, and their telomers shorten until the chromosome is unable to replicate. Immortal cells have short but stable chromosomes and increased telomerase activity. Transitional cell carcinoma (TCC) has only a few useful markers of diagnostic or prognostic importance. The objective of this study was to determine whether there was a correlation between telomerase activity and the grade or stage of TCC, and whether the enzyme's activity could serve as a biochemical marker of this tumor. METHODS: The study included 29 patients with TCC. From each patient, samples of urine cells were obtained, and a cup biopsy was taken from an apparently normal area as well as from a part of the bladder tumor resected transurethrally. Control uroepithelial biopsies were taken from normal transitional cell sites from non-TCC patients. Biopsies or cells were subjected to either histologic examination or telomerase activity determination. RESULTS: Twenty-six of 29 (90%) of the tumor biopsies exhibited telomerase activity. Most of the cup biopsies were categorized as metaplastic or dysplastic, and 20 of 29 (69%) of these exhibited telomerase activity. Telomerase activity was found in 17 of 21 (81%) of the urine cells but in only 3 of 14 (21%) of control urine cells. All (10 of 10) of the uroepithelial biopsies taken from non-TCC patients did not show any telomerase activity. CONCLUSIONS: In this study, almost all tumor biopsies exhibited telomerase activity. The high incidence of telomerase activity found in cup biopsies of the malignant field uroepithelial cells from cup biopsies of TCC patients may suggest that telomerase could be activated early in carcinogenesis. A high incidence of telomerase activity was found in voided uroepithelial cells of TCC patients; however, no correlation between this activity and the histologic determination of grading and staging of the tumor was found.

Aged↗
PubMed1999

A signal encoded in vertebrate DNA that influences nucleosome positioning and alignment.

Evidence is provided that the nucleotide triplet con-sensus non-T(A/T)G (abbreviated to VWG) influences nucleosome positioning and nucleosome alignment into regular arrays. This triplet consensus has been recently found to exhibit a fairly strong 10 bp periodicity in human DNA, implicating it in anisotropic DNA bendability. It is demonstrated that the experimentally determined preferences for nucleosome positioning in native SV40 chromatin can, to a large extent, be pre-dicted simply by counting the occurrences of the period-10 VWG consensus. Nucleosomes tend to form in regions of the SV40 genome that contain high counts of period-10 VWG and/or avoid regions with low counts. In contrast, periodic occurrences of the dinucleotides AA/TT, implicated in the rotational positioning of DNA in nucleosomes, did not correlate with the preferred nucleosome locations in SV40 chromatin. Periodic occurrences of AA did correlate with preferred nucleosome locations in a region of SV40 DNA where VWG occurrences are low. Regular oscillations in period-10 VWG counts with a dinucleosome period were found in vertebrate DNA regions that aligned nucleosomes into regular arrays in vitro in the presence of linker histone. Escherichia coli and plasmid DNA, which fail to align nucleosomes in vitro, lacked these regular VWG oscillations.

Animals↗
PubMed1999

In search of spatial extremes.

In environmental studies attention increasingly focuses on identification of spatial extremes: locations with observations that are apparently higher than either a preset background threshold or neighbouring observations. We consider various procedures for identifying values and locations of these extremes: extreme value theory, conditionally simulated fields and disjunctive kriging. In a recent research project we studied the distribution of nine environmental pollutants (heavy metals, polyaromatic hydrocarbons and mineral oil) in a large industrial estate in the southern Netherlands. This area is interesting as it is influenced by three contaminating processes: inundation by the river Meuse, anthropogenic heightening with contaminated materials and local industrial activities. Concentrations are measured. In this paper the peaks over threshold method was useful for finding extremes for spatially uncorrelated variables, whereas conditional simulations applied in particular to areas with spatial dependence.

Animals↗
PubMed1999

Phase II trial of intraperitoneal cisplatin with intravenous doxorubicin and cyclophosphamide in previously untreated patients with advanced ovarian cancer-long-term follow-up.

Forty-three patients with ovarian cancer were entered on this trial and treated with intravenous (iv) cyclophosphamide (C) and doxorubicin (A), and intraperitoneal (ip) cisplatin (DDP), every 21 days for eight cycles. Following iv hydration, the cisplatin was administered through an intraperitoneal catheter in 2 L of 0.9% normal saline with a 4-h dwell. All patients are evaluable for overall and progression-free survival with a median follow-up of 70 months (range: 3-162 months); 39 patients are evaluable for response. All complete responses were surgically confirmed. The median age was 59 (range 28-82 years); 3 patients were stage IC, 5 were IIC, 14 patients were stage III (optimally debulked), 14 patients were stage III (suboptimally debulked), and 7 patients were stage IV. Two patients had received prior alkylator therapy. Six of 8 patients with Stage IC or II remain without evidence of disease at a mean of 12 years following chemotherapy. Of 14 optimally debulked stage III patients, there were 7 complete responses, 3 partial responses, 1 patient with stable disease, and 3 inevaluable patients. Of 14 suboptimally debulked stage III patients there were 4 complete responses, 4 partial responses, 3 with stable disease, 2 progressions on treatment, and 1 inevaluable patient. Five-year progression-free and overall survivals for stage III optimally debulked patients are 21 and 64%, respectively. At 10 years, progression-free and overall survivals for this group are 21 and 29%, respectively. Toxicity included neutropenia (complicated by sepsis in 2 patients), infrequent thrombocytopenia, and mild anemia. Three patients developed transient serum creatinine elevations >2.0 mg/dl; however, decreased creatinine clearance was noted in 93/258 (36%) of evaluable courses which required a cisplatin dose reduction per protocol. Controllable hypomagnesemia, nausea, and emesis were also observed. We conclude that the combination of iv CA and ip DDP is an effective regimen with long-term progression-free and overall survivals that compare favorably with those of other published studies of intravenous or intraperitoneal chemotherapy. This report is unusual in terms of the prolonged follow-up for all patients enrolled. These long-term results lend further support to recently published trials documenting the efficacy of intraperitoneal chemotherapy for patients with this disease.

Adult↗
PubMed1999

Pulmonary lymphangioleiomyomatosis: high-resolution CT findings.

Lymphangioleiomyomatosis (LAM) of the lung is a very rare disease. There are obvious discrepancies in the literature concerning the appearance of LAM on CT scans of the lung. This study adds the imaging findings of 11 patients and demonstrates how the imaging findings changed over time in four patients. Twenty-two CT examinations, and radiographs that had been obtained close to the CT examinations, of 11 patients with LAM confirmed by open lung biopsy were retrospectively evaluated with particular attention to the size of cystic lesions and wall thickness. Furthermore the CT scans were analysed for the type of pulmonary infiltration process and its distribution, presence or absence of pleural effusion, pneumothorax and lymph node enlargement. Clinical and CT follow-up studies were available in four patients. The CT scans revealed an increase in the interstitial pattern in all patients. Architectural distortion was seen in two patients and cystic lesions were present in all. The size of the cysts varied from small lesions to bullous emphysema. The cystic lesions revealed a wall thickness up to 2 mm but a wall was not perceptible in all. Pneumothorax was seen in only two patients; pleural effusion was seen in two patients. CT examination of patients with LAM reveals neither a uniform nor a pathognomonic appearance. In the early stages of LAM or in cases with interstitial changes the differential diagnosis of centrilobular emphysema or idiopathic pulmonary fibrosis seems to be more difficult than most authors believe.

Adolescent↗
PubMed1999

High-dose chemo/radiotherapy and autologous bone marrow or stem cell transplantation for poor-risk advanced-stage Hodgkin's disease during first partial or complete remission.

Complete remission rates of 70-90% can be achieved following combination chemotherapy for patients with advanced-stage Hodgkin's disease (HD). Patients who present with unfavorable poor prognostic factors, however, have a 5-year disease-free survival of only 40-50%. In an attempt to improve the prognosis of 20 patients with poor-risk advanced-stage HD, we evaluated the role of early high-dose therapy (HDT) and autologous bone marrow/stem cell transplantation (ASCT) during the first complete or partial remission (CR/PR). Patients were eligible for ASCT if they either achieved a PR (defined as > 50% regression) (six patients), or achieved a CR (14 patients) but had presented with three or more of the following unfavorable features: stage IV disease with bone marrow involvement or > or = 2 extranodal sites of involvement; bulky mass > 10 cm or bulky mediastinal mass > 1/3 of mediastina/thoracic ratio; B symptoms; and elevated serum lactate dehydrogenase (LDH) level. The study included 11 men (55%) and 9 women (45%). The median age was 37 years (range 20-57). Seventeen patients (85%) had stage IV disease; 14 (70%) had B symptoms; 13 (65%) had bulky mass > 10 cm; 14 (70%) had > or = 2 extra nodal sites involvement; and eight patients (40%) had elevated LDH levels. All patients were treated with standard four or 7-8 drug combination chemotherapy regimens until they achieved maximal response prior to ASCT with a median of six cycles (range 4-11). Six patients also received involved field radiotherapy to residual bulky mass > 5 cm or bony lesions before ASCT. The median time from diagnosis to ASCT was 8.6 months (range 5.5-18.9). Preparative regimens consisted of fractionated total body irradiation (FTBI) 1200 cGy in combination with etoposide 60 mg/kg and cyclophosphamide 100 mg/kg in all patients except one who had borderline pulmonary function and received lomustine 15 mg/kg instead of FTBI. All patients engrafted and there was no transplant-related mortality. One patient developed congestive cardiomyopathy at 4 years post-ASCT. All patients remain alive and in remission at a median follow-up of 42.8 months (range, 13.2-149.2). These preliminary results suggest that HDT and ASCT can be performed safely during first CR/PR in selected patients with advanced-stage HD who have an unfavorable prognosis. Further randomized studies comparing HDT and ASCT during first CR with conventional chemotherapy and ASCT at relapse in poor-risk advanced-stage HD should be conducted. The prognostic factors and risk groups described recently by an international prognostic study can be used to identify high-risk patients who may be candidates for more intensive therapy.

Adult↗
PubMed1999

Functional consequences of mutations in the conserved 'signature sequence' of the ATP-binding-cassette protein MalK.

The binding-protein-dependent maltose-transport system of enterobacteria, a member of the ATP-binding-cassette (ABC) transporter superfamily, is composed of two integral membrane proteins, MalF and MalG, and two copies of an ATPase subunit, MalK, which hydrolyze ATP, thus energizing the translocation process. Isolated MalK displays spontaneous ATPase activity, whereas in the assembled MalFGK2 complex, reconstituted in liposomes, ATP hydrolysis requires stimulation by the substrate-loaded extracellular maltose-binding protein, MalE. The ATPase domains of ABC transporters, including MalK, share a unique sequence motif ('LSGGQ', 'signature sequence' or 'linker peptide') with as yet unknown function. To elucidate its role in the transport process, we investigated the consequences of mutations affecting two highly conserved residues (G137, Q140) in the MalK-ATPase of Salmonella typhimurium, by biochemical means. Residues corresponding to Q140 in other ABC proteins have not yet been studied. All mutant alleles (G137--> A, V, T; Q140--> L, K, N) fail to restore a functional transport complex in vivo. In addition, the mutations increase the repressing activity of MalK on other maltose-regulated genes when compared with wild-type MalK. Purified variants of G137 have lost the ability to hydrolyze ATP but still display nucleotide-binding activity, albeit with reduced affinity. Binding of MgATP results in similar protection against trypsin, as observed with wild-type, indicating no major change in protein structure. In contrast, the variants of Q140 differ in their properties, depending on the chemical nature of the replacement residue. MalKQ140L fails to hydrolyze ATP and exhibits a strong intrinsic resistance to trypsin in the absence of MgATP, suggesting a drastically altered conformation. In contrast, the purified mutant proteins Q140K and Q140N display ATPase activities and MgATP-induced changes in the tryptic cleavage pattern similar to those of wild-type. However, mutant transport complexes containing the Q140K or Q140N variants, when studied in proteoliposomes, are severely impaired in MalE-maltose-stimulated ATPase activity. These results are discussed with respect to the crystal structure of the homologous HisP protein [Hung, L.-W., Wang, I.X., Nikaido, K., Liu, P.-Q., Ames, G.F.-L. & Kim, S.-H. (1998) Nature (London) 396, 703-707] and are interpreted in favor of a role of the signature sequence in activating the hydrolyzing activity of MalK upon substrate-initiated conformational changes in MalF/MalG.

ATP-Binding Cassette Transporters↗
PubMed1999

Interleukin-2-activated autologous bone marrow and peripheral blood stem cells in the treatment of acute leukemia and lymphoma.

In this pilot trial of interleukin (IL)-2-treated autologous bone marrow (BM) and peripheral stem cell (PSC)-supported high-dose chemoradiotherapy, we report 36 patients with poor-prognosis leukemia and lymphoma who received BM and/or granulocyte colony-stimulating factor (G-CSF)-mobilized autologous PSCs that had been exposed to IL-2 for 24 hours ex vivo. Patients then received IL-2 by low-dose continuous intravenous (i.v.) infusion until hematologic reconstitution and then by intermediate-dose continuous i.v. infusion for six 2-week maintenance cycles given at 1-month intervals. The median Day to neutrophils over 500/microL was 22 with BM and 10 with PSCs (p = 0.01). The median Day to platelets >20,000/microL was 50 for BM and 25 for PSCs, and to platelets >50,000/microL was 138 for BM and 34 for PSCs (p not significant). After the first three patients received IL-2 at 2 mIU x m(-2) x day(-1) and had slow reconstitution, four patients were treated without IL-2 until the maintenance phase following reconstitution. The remaining 29 patients received the initial "post-infusion" IL-2 at 1 mIU x m(-2) x day(-1). Toxicities associated with the infusion of IL-2-activated cells consisted of chills and fever in about one-half of the patients and transient hypotension in 12%. Low-dose IL-2 by continuous i.v. infusion in the early posttransplant period was associated with exacerbation of fever, diarrhea, and altered mental status in a minority of patients. The major dose-limiting toxicities of maintenance IL-2 were fever, fatigue, gastrointestinal symptoms, skin rash, and dyspnea. Among 24 lymphoma patients, nine are in continuous complete remission (CCR) from 18-48 months, and 15 have died (12 due to relapse and three of therapy-related toxicities). Of 12 acute leukemia patients, two with acute lymphoblastic leukemia (ALL) are in CCR at 38 and 43 months, and one patient who was in cytogenetic but not molecular remission of Philadelphia chromosome-positive ALL died of progressive leukemia at Day 108. Three of nine with myeloid leukemia are in CCR at 21, 46, and 53 months; one is in hematologic and cytogenetic remission of acute promyelocytic leukemia at 55 months with multiple new cytogenetic abnormalities; one is alive at 54 months with pancytopenia after incomplete hematologic recovery followed by multiple new cytogenetic abnormalities (myelodysplasia); and one had an unrelated donor transplant after relapsing 4 months following protocol therapy. One myeloid leukemia patient remains without evidence of relapse, but is transfusion-dependent at 15 months following transplant.

Acute Disease↗
PubMed1999

Pigeon pneumonia in provence: a bird-borne Q fever outbreak.

Q fever is a widespread zoonosis caused by Coxiella burnetii, an obligate intracellular bacterium, which humans usually acquire through the inhalation of infected dust from subclinically infected mammals. Human infection commonly takes place when an infected mammal gives birth, since high concentrations of the organism are found in the products of conception. Worldwide, cattle, sheep, and goats are the most common reservoirs for C. burnetii. A few investigators have also reported parturient cats and dogs as the sources of human outbreaks of Q fever. During a 10-day period in May 1996, all five members of one family living on a farm in Provence, in the south of France, became ill with fever, general malaise, and cough. All of them had acute Q fever. An epidemiological investigation suggested that this outbreak resulted from exposure to contaminated pigeon feces and ticks.

Adult↗