Search PubMed⌕ Search

Biomedical subjects

J Miller

Publications and source records attributed to J Miller.

At least 559 records · Page 31Linked to original sources
PubMed1994

Strength training increases resting metabolic rate and norepinephrine levels in healthy 50- to 65-yr-old men.

Resting metabolic rate (RMR) decreases with age, largely because of an age-related decline in fat-free mass (FFM). We hypothesized that a strength-training program capable of eliciting increases in FFM would also increase RMR in older individuals. To test this hypothesis, RMR, body composition, and plasma concentrations of certain hormones known to affect RMR were measured before and after a 16-wk heavy-resistance strength-training program in 13 healthy men 50-65 yr of age. Average strength levels, assessed by the three-repetition maximum test, increased 40% with training (P < 0.001). Body weight did not change, but body fat decreased (25.6 +/- 1.5 vs. 23.7 +/- 1.7%; P < 0.001) and FFM increased (60.6 +/- 2.2 vs. 62.2 +/- 2.1 kg; P < 0.01). RMR, measured by indirect calorimetry, increased 7.7% with strength training (6,449 +/- 217 vs. 6,998 +/- 226 kJ/24 h; P < 0.01). This increase remained significant even when RMR was expressed per kilogram of FFM. Strength training increased arterialized plasma norepinephrine levels 36% (1.1 +/- 0.1 vs. 1.5 +/- 0.1 nmol/l; P < 0.01) but did not change fasting glucose, insulin, or thyroid hormone levels. These results indicate that a heavy-resistance strength-training program increases RMR in healthy older men, perhaps by increasing FFM and sympathetic nervous system activity.

Aged↗
PubMed1994

Switching or sharing in dual-task line-length discrimination?

In two experiments, we tested whether subjects switched or shared attention between two simultaneously relevant line-length discrimination tasks. Switching models that allowed within- as well as between-trial switching were considered. In the first experiment, stimulus duration was varied randomly from trial to trial. With varied durations, many switching models predict negative contingencies: for a given duration and attentional allocation, accurate responses on one task should be associated with inaccurate responses on the other task. The results, however, showed no negative contingencies, which is consistent with sharing models. In the second experiment, stimulus duration was reduced to 20 msec, yet responses were more than 75% correct overall. This implies that information was obtained about both of the tasks within single trials, contradicting those switching models which predict that information can be obtained from, at most, one task within a period of 20 msec or less. In short, the results of both experiments support sharing models.

Attention↗
PubMed1994

Attentional effects on concurrent psychophysical discriminations: investigations of a sample-size model.

In two experiments, a concurrent discrimination paradigm was used to study the effects of visual attention on psychophysical judgments and the consistency of these effects with a sample-size model in which attention influences the variance of the internal representation used to make psychophysical judgments. Two pairs of lines were presented simultaneously--one on each side of fixation--and subjects had to indicate for each pair separately whether or not the lines had the same length. Attention was manipulated by instructing subjects to pay 100%, 75%, 50%, 25%, or 0% of their attention to the discrimination on one side, with the complementary amount of attention to the other side. In the first experiment, the relationship between attention and discrimination accuracy was consistent with the sample-size model both when attentional allocation varied from trial to trial and when it varied between blocks, and the relationship held over more widely varying attentional allocations than had previously been studied. In addition, discriminations were more accurate overall with varied than with blocked attentional allocation, suggesting that the two types of allocation do not merely differ in the degree to which attention is focused. The second experiment examined the effects of attentional allocation and stimulus variance, the latter being manipulated by randomly incrementing or decrementing line lengths. These manipulations had additive effects on total Thurstonian variance, and a version of the sample-size model gave an excellent quantitative fit to the obtained results. Besides supporting the sample-size model, the results of Experiment 2 suggest that criterion variance is at least as large as sensory variance and that criterion but not sensory variance increases with stimulus variance.

Attention↗
PubMed1994

Nonperturbative methods in HZE propagation.

An analytical solution to the perturbative multiple collision series of a fragmenting HZE ion beam has limited usefulness since the first collision term has several hundred contributions, the second collision term has tens of thousands of contributions, and each successive collision term progresses to unwieldy computational proportions. Our previous work has revealed the multiple collision terms in the straight-ahead approximation to be simple products of a spatially dependent factor times a linear energy-dependent factor of limited domain and unit normalization. The properties of these forms allow the development of the nonperturbative summation of the series to all orders assuming energy-independent nuclear cross sections as matrix products of a scaled Green's function described herein. This nonperturbative Green's function with multiple scattering correction factors compares well with experiments using 670 MeV/u neon-20 ion beams in thick water targets.

Cosmic Radiation↗
PubMed1994

Cloning and expression of the cDNA for canine tumor necrosis factor-alpha in E. coli.

We have utilized the reverse transcription polymerase chain reaction (RT-PCR) to clone the protein coding region of canine tumor necrosis factor (TNF-alpha) cDNA. The gene displays 90% sequence homology to the corresponding human TNF-alpha cDNA. The predicted initial translation product is 233 amino acids and shows 88% homology to the human counterpart, and 92% homology with the human putative mature TNF-alpha protein. The canine TNF-alpha clone was used to engineer bacteria to express large amounts of the mature form of recombinant protein. A monoclonal antibody against human TNF-alpha cross-reacted with canine rTNF-alpha using Western blot and ELISA analysis. The purified canine rTNF-alpha had a cytotoxic effect on WEHI 164 clone 13 cells as well as increasing the cell surface expression of major histocompatibility class II antigens on canine kidney cortical cell line (MDCK) in vitro. The availability of canine rTNF-alpha will allow further studies on its role in immunoregulatory mechanisms in the canine transplantation model, both by itself and in conjunction with the already available canine specific recombinant interferon-gamma.

Amino Acid Sequence↗
PubMed1994

Interaction of primitive human myeloid and lymphoid progenitors with the marrow microenvironment.

Primitive human hematopoietic progenitors containing a high proportion of long-term culture-initiating cells (LTCICs) are found in the 34+DR- fraction of bone marrow mononuclear cells (BMMNCs). These progenitors adhere selectively to the 33/66-kD binding domain of fibronectin and to the FN-CHII binding site, unlike more committed progenitors, which adhere less selectively to fibronectin components. These differences in adhesion to stromal components may explain selective homing and release of progenitors at varying levels of differentiation from the marrow compartment. In additional studies, we demonstrate that cultivation of primitive progenitors in a stroma noncontact long-term culture allows both differentiation of primitive progenitors and conservation of LTCICs. These observations (1) demonstrate that expansion of primitive progenitors does not require stromal contact, (2) shed light on the regulatory role of stroma in myeloid differentiation, and (3) suggest strategies for both ex vivo myeloid progenitor expansion and retrovirus gene insertion. Finally, we demonstrate that a natural killer cell population can be derived from primitive hematopoietic progenitors in a modified long-term culture model. Our findings suggest an important role for marrow stroma in lymphoid differentiation from primitive progenitors and in expression of CD2, a lymphoid marker ordinarily associated with passage of T-lymphocyte progenitors through the thymus.

Bone Marrow Cells↗
PubMed1994

Diagnosis and management of bile leaks following laparoscopic cholecystectomy.

Laparoscopic cholecystectomy is now the standard of care for the elective management of gallstone disease. Recent studies have shown the morbidity of laparoscopic cholecystectomy to be similar to that of open cholecystectomy. Postoperative bile leaks have been recognized to be a troublesome problem following laparoscopic cholecystectomy. We present a retrospective review of 854 patients undergoing laparoscopic cholecystectomy at a single institution. Records were reviewed of all patients identified as having postoperative bile leaks. Between January 1990 and April 1991, we have cared for, or been referred, 15 patients with postlaparoscopic cholecystectomy bile leaks (9/854, 1.1% index patients and 6 referred). The location of bile leakage was determined to be the common bile duct (CBD) in two, cystic duct in five, and small accessory ducts located close to the gallbladder bed in the remaining eight. Most patients presented in the first week following laparoscopic cholecystectomy (mean 4.3 +/- 0.7 days, range 2-10) with worsening abdominal pain (13/13, 100%), nausea, and low-grade fever (mean 99.6 +/- 0.3 degrees F, range 96.8-102.2). Eleven of fifteen (66.7%) patients underwent technectium-99m imidodiacetic acid scanning (Tc-99m IDA) to determine the presence of a possible bile leak. All eleven scans were positive, indicating the presence of a bile leak. Thirteen patients underwent endoscopic cholangiography confirming the presence of biliary leakage (the remaining two patients underwent prompt laparotomy). Five patients were taken to the operating room for management of their leaks (two with common bile duct injuries, two cystic duct leaks, one accessory duct leak).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[HIV infection and AIDS in urology].

Up to December 1993, a total of 10858 AIDS cases were reported to the central AIDS registry at the Federal Health Office. Human immunodeficiency virus is acquired through needle sharing (i.v. drug users), contaminated blood transfusions, intercourse with infected persons and transplacentally by fetuses. In Germany, about seven people a day are estimated to acquire the HIV infection. Half the patients will develop systemic manifestations of AIDS within 12-13 years. Only a small percentage of these patients suffer from urological manifestations, e.g. urinary tract infection, prostatism or HIV-associated nephropathy. Nevertheless, knowledge of genitourinary pathology caused by HIV makes early diagnosis of AIDS possible.

AIDS-Related Opportunistic Infections↗
PubMed1994

Preoperative assessment of skin colonization and antibiotic effectiveness in total knee arthroplasty.

A bacteriologic screening procedure was performed to preoperatively assess the skin flora of 152 total knee arthroplasty patients and to determine the appropriate prophylactic antibiotic and skin-cleansing technique. Staphylococcus epidermidis resistant to standard prophylactic antibiotics was present in 4.6% of patients, whereas 44% of the patients had Staphylococcus aureus, which is poorly eradicated by standard cleansing techniques. Preoperative assessment of skin colonization has demonstrated that standard preoperative antibiotics and skin-cleansing techniques will not completely eradicate all pathogenic skin bacteria in every case. Preoperative screening effectively identifies bacterial skin flora and allows for the modification of antibiotic selection and preoperative cleansing to eradicate resistant bacterial organisms and thereby decrease the risk of postoperative prosthetic infections.

Adult↗
PubMed1993

Crystallization and preliminary X-ray analysis of leukemia inhibitory factor.

Leukemia inhibitory factor (LIF) is a polyfunctional molecule with significant and diverse biological activities. LIF is a glycoprotein secreted by a number of different cell types in vitro. It is induced in fibroblasts, lymphocytes, monocytes and astrocytes by various inducers such as serum, TNF, interleukin-IP and EGF. Due to extensive and variable glycosylation the molecular weight can range from 38 to 67 kDA. The biological functions of LIF are mediated through a receptor and a signal transducer, gp130, which is also used by factors like interleukin-6 (IL-6), cilliary neurotropic factor (CNTF), and oncostatin M (OSM). Here, we report the crystallization of the non-glycosylated human-like LIF expressed in E. coli. The present crystals diffract to 2.0 A using synchrotron radiation. They belong to the monoclinic space group C2, and the cell dimensions are a = 61.5 A, b = 45.3 A, c = 77.7 A and beta = 112.3 degrees.

Cloning, Molecular↗
PubMed1993

Expression and functional significance of an additional ligand for CTLA-4.

Effective T-cell activation requires antigen/major histocompatibility complex engagement by the T-cell receptor complex in concert with one or more costimulatory molecules. Recent studies have suggested that the B7 molecule, expressed on most antigen presenting cells, functions as a costimulatory molecule through its interaction with CD28 on T cells. Blocking the CD28/B7 interaction with CTLA4Ig inhibits T-cell activation in vitro and induces unresponsiveness. We demonstrate that another molecule(s), termed B7-2, is expressed constitutively on dendritic cells, is differentially regulated on B cells, and costimulates naive T cells responding to alloantigen. B7-2 is up-regulated by lipopolysaccharide in < 6 hr and is maximally expressed on the majority of B cells by 24 hr. In contrast, B7 is detected only on a subset of activated B cells late (48 hr) after stimulation. In addition, Con A directly induces B7-2 but not B7 expression on B cells. Finally, although both anti-B7 monoclonal antibodies and CTLA4Ig blocked T-cell proliferation to antigen-expressing B7 transfectants, only CTLA4Ig had any significant inhibitory effect on T-cell proliferation to antigens expressed on natural antigen presenting cells, such as dendritic cells. Thus, B7 is not the only costimulatory molecule capable of initiating T-cell responses since a second ligand, B7-2, can provide a necessary second signal for T-cell activation.

Abatacept↗
PubMed1993

Enhanced antigen presentation in the absence of the invariant chain endosomal localization signal.

The cytosolic tail of the major histocompatibility complex class II-associated invariant chain (Ii) molecule is thought to contain the endosomal localization signal that directs and/or retains newly synthesized class II within the endosomal antigen processing compartment. To determine the role of this signal in class II transport and antigen presentation we have generated class II-positive L cell transfectants that coexpress wild type or truncated forms of Ii. Deletion of the endosomal localization signal from Ii results in rapid transport of class II-Ii complexes to the cell surface. Once at the cell surface, the complex is efficiently internalized, Ii is degraded, and class II free of Ii is recycled back to the plasma membrane. Interestingly, the truncated form of Ii is still able to increase the efficiency of antigen presentation to T cells. These data suggest that the ability of Ii to enhance antigen presentation is not limited to Golgi apparatus-endosomal sorting and raise the possibility that endocytosed class II can form immunogenic complexes with newly processed antigen.

Amino Acid Sequence↗
PubMed1993

The chondroitin sulfate form of invariant chain can enhance stimulation of T cell responses through interaction with CD44.

Invariant chain (Ii) is a nonpolymorphic glycoprotein that associates with major histocompatibility complex class II molecules and has been shown to mediate several functions in class II-restricted antigen presentation. A small proportion of Ii is modified by the addition of chondroitin sulfate (Ii-CS), and this form of Ii is associated with class II on the surface of antigen-presenting cells. In this report we show that expression of Ii-CS dramatically enhanced the ability of class II-positive EL4 transfectants to stimulate class II-dependent allogeneic and mitogenic T cell responses. Antibody blocking studies and the ability of CD44 to bind directly to Ii-CS suggest that Ii-CS can function as an accessory molecule during T cell responses through interactions with CD44.

Animals↗