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Biomedical subjects

C Zimmerman

Publications and source records attributed to C Zimmerman.

At least 19 recordsLinked to original sources
PubMed1998

Regulation of E2F4 mitogenic activity during terminal differentiation by its heterodimerization partners for nuclear translocation.

E2F/DP heterodimers play a pivotal role in the regulation of cell growth and differentiation. A decrease in E2F/DP activity occurs during cell cycle arrest and differentiation. However, very little is known about the specific role of the various E2F/DP members along the transition from proliferation to terminal differentiation. We have previously shown that E2F4 accounts for the vast majority of the endogenous E2F in differentiating muscle cells. Here, we show that E2F4, which lacks a nuclear localization signal (nls), is distributed in both the nucleus and the cytoplasm, in either asynchronously growing myoblasts or differentiated myotubes. E2F4 nuclear accumulation is induced by the binding in the cytoplasm with specific partners p107, pRb2/p130, and DP3delta, an nls-containing spliced form of DP3, which provide the nls. Although overexpression of E2F4/DP3delta reactivates the cell cycle in quiescent cells, the E2F4 nuclear accumulation induced by pRb2/p130 and p107 correlates with cell growth arrest Moreover, E2F4/DP3delta-induced cell cycle reactivation is efficiently counteracted by either p107 or pRb2/p130 overexpression. Reinduction in quiescent cells of DNA synthesis by E2F1/DP1 overexpression is abrogated by coexpression of pRb and is hampered by MyoD overexpression. Both pRb2/p130 and pRb, as well as MyoD, are up-regulated in myotubes. Accordingly, multinucleated myotubes, which are induced to reenter the S-phase by oncoviral proteins, are refractory to cell cycle reactivation by forced expression of E2F4/DP3delta or E2F1/DP1. Thus, E2F/DP repression represents only one of multiple redundant circuits that control the postmitotic state in terminally differentiated cells and that are targeted by adenovirus E1A and SV40 large T antigen.

Animals↗
PubMed1998

Constitutive expression of Bcl-xL or Bcl-2 prevents peptide antigen-induced T cell deletion but does not influence T cell homeostasis after a viral infection.

We examined the CD8+ T cell response to lymphocytic choriomeningitis virus (LCMV) in mice doubly transgenic for an LCMV-specific TCR and for either bcl-xL or bcl-2. Clonal down-sizing of the anti-viral CD8+ T cell response and the generation of T cell memory was not influenced by constitutive expression of these anti-apoptotic proteins in T cells. Expression of Bcl-xL or Bcl-2 did, however, prevent LCMV peptide-induced peripheral deletion of mature CD8+ T cells in vivo and apoptosis of activated LCMV-specific effector T cells in vitro. The CD8+ T cells "rescued" by Bcl-xL or Bcl-2 from peptide antigen-induced cell death were anergic and this could not be reversed by addition of IL-2 in vitro or by adoptive transfer into antigen-free recipient mice followed by LCMV infection in vivo. Taken together, we show here that 1) Bcl-xL or Bcl-2 are functionally equivalent in their ability to modulate CD8+ T cell survival in vivo, 2) distinct apoptosis signaling pathways exist in CD8+ T cells, one that can be inhibited by Bcl-2 or Bcl-xL and one that cannot be blocked, and 3) apoptosis of CD8+ effector T cells during the declining phase of an immune response is not prevented by constitutive expression of the anti-apoptotic proteins Bcl-xL and Bcl-2.

Animals↗
PubMed1997

Prior experience and complex procedures.

The role of prior knowledge in learning complex procedures was investigated in a transfer task in which subjects learned two related procedures in sequence. In Experiment 1, we manipulated the conceptual and structural similarity between the two procedures; in Experiment 2, we manipulated whether the order of the steps within subprocedures was the same or different during training and transfer, or whether the order of the subprocedures was the same or different. The results lead us to hypothesize that transfer in complex procedures is mediated primarily by a memory for specific steps rather than by conceptual understanding or problem solving. In particular, we were able to model the results precisely on the assumption that subjects use superficial similarity to retrieve the sequences of steps needed to perform segments of the procedure.

Humans↗
PubMed1996

Response of primary leptomeningeal melanoma to intrathecal recombinant interleukin-2. A case report.

BACKGROUND: Primary leptomeningeal melanomas are rare tumors that originate in the leptomeninges and are associated with a poor prognosis and no response to radiation and chemotherapy. These tumors rarely metastasize outside the central nervous system. Recombinant interleukin-2-(rIL-2) is a cytokine that activates natural killer cells and lymphokine-activated killer cells, augments their antitumor effects, and recruits and activates cytotoxic T lymphocytes. We have hypothesized that rIL-2 may prolong disease free survival in a patient with primary leptomeningeal melanoma. METHODS: The patient was treated with intrathecal rIL-2 via lumbar puncture daily for 5 days, the weekly for 5 weeks. To investigate whether rIL-2 induced a favorable clinical response, the following parameters were monitored: survival, neurologic status, cerebrospinal fluid (CSF) analysis, visual fields, and magnetic resonance imaging (MRI) of the lumbosacral spine. RESULTS: The patient is still alive and disease free 15 months after receiving rIL-2, and his neurologic status remains unchanged. The CFS glucose concentration, undetectable prior to therapy, has become normal. Repeated cytologic examinations of CSF were negative for malignant cells. The visual field examinations have remained unchanged. MRI scans of the lumbosacral spine have shown the development of arachnoiditis, but no recurrence of the mass lesion. CONCLUSIONS: The tumor response in this patient, as measured by remarkable disease free survival and normalization of the CSF glucose concentration, illustrates the potential benefits of intrathecal rIL-2 in the treatment of patients with this otherwise rapidly fatal disease.

Animals↗
PubMed1996

Visualization, characterization, and turnover of CD8+ memory T cells in virus-infected hosts.

The cellular basis of T cell memory is a controversial issue and progress has been hampered by the inability to induce and to trace long-term memory T cells specific for a defined antigen in vivo. By using the murine model of lymphocytic choriomeningitis virus (LCMV) infection and an adoptive transfer system with CD8+ T cells from transgenic mice expressing an LCMV-specific T cell receptor, a population of authentic memory T cells specific for LCMV was generated and analyzed in vivo. The transgenic T cells that have expanded (1,000-fold) and then decreased (10-fold) in LCMV-infected C57BL/6 recipient mice exhibited the following characteristics: they were (a) of larger average cell size than their naive counterparts but smaller than day 8 effector cells; (b) heterogeneous with respect to expression of cell surface "memory" markers; and (c) directly cytolytic when isolated from recipient spleens. The time-dependent proliferative activity of these LCMV-specific memory T cells was analyzed in the recipients by bromodeoxyuridine labeling experiments in vivo. The experiments revealed that LCMV-specific CD8+ memory T cells can persist in LCMV-immune mice for extended periods of time (>2 mo) in the absence of cell division; the memory population as a whole survived beyond 11 mo.

Amino Acid Sequence↗
PubMed1996

A controlled trial of remacemide hydrochloride in Huntington's disease.

We conducted a randomized, double-blind, placebo-controlled tolerability study of a N-methyl-D-aspartate (NMDA) glutamate receptor ion-channel blocker, remacemide hydrochloride, in 31 independently ambulatory patients (18 men, 13 women) with Huntington's disease (HD). Subjects were randomized to receive either placebo or active remacemide at dosages of 200 mg/day or 600 mg/day. The primary outcome measure was the proportion of subjects able to complete the study with the assigned treatment. Remacemide was generally well tolerated, and no significant differences between the treatment arms were found in the primary outcome measure. A trend toward improvement in chorea was observed among subjects administered remacemide 200 mg/day. Based on the tolerability and safety demonstrated during this short-term trial, remacemide warrants more extended controlled investigation in patients with HD.

Acetamides↗
PubMed1996

Assessment of coenzyme Q10 tolerability in Huntington's disease.

We performed a 6-month open-label trial to evaluate the tolerability and efficacy of coenzyme Q10 (CoQ) in 10 patients with Huntington's disease (HD). Subjects were evaluated at baseline, 3 months, and 6 months using the HD Rating Scale (HDRS), the HD Functional Capacity Scale (HDFCS), and standardized neuropsychological measures. Adverse events (AEs) were assessed by telephone interview every month. CoQ doses ranged from 600 to 1,200 mg per day. All subjects completed the study, although four subjects reported mild AEs, including headache, heartburn, fatigue, and increased involuntary movements. There was no significant effect of the treatment on the clinical ratings. The good tolerability of CoQ suggests that it is a good candidate for evaluation in long-term clinical trials designed to slow the progression of HD.

Activities of Daily Living↗
PubMed1996

Psychogenic status epilepticus induced by a provocative technique.

We report a patient who developed sustained psychogenic seizures after undergoing a provocative technique (PT) for the diagnosis of psychogenic seizures. Because patients are at risk for severe agitation with PT, these diagnostic maneuvers should be used selectively, and the clinician should be prepared to deal with this complication.

Adult↗
PubMed1995

Functional decline in Huntington's disease.

We prospectively evaluated 129 patients with manifest Huntington's disease (HD) to determine the rate of illness progression and the clinical features that correlate with functional decline. A single examiner evaluated each patient using the HD Functional Capacity Scale. Standardized motor performance was also assessed in 94 of the patients (73%) using the HD Rating Scale. Total Functional Capacity declined at a rate of 0.63 +/- 0.75 U per year. As functional capacity worsened, chorea lessened, and dystonia intensified. There was no correlation between rate of functional decline and age at onset of HD, body weight, gender of affected parent, or history of neuroleptic use.

Adolescent↗
PubMed1994

Trinucleotide repeat length and progression of illness in Huntington's disease.

The genetic defect causing Huntington's disease (HD) has been identified as an unstable expansion of a trinucleotide (CAG) repeat sequence within the coding region of the IT15 gene on chromosome 4. In 50 patients with manifest HD who were evaluated prospectively and uniformly, we examined the relationship between the extent of the DNA expansion and the rate of illness progression. Although the length of CAG repeats showed a strong inverse correlation with the age at onset of HD, there was no such relationship between the number of CAG repeats and the rate of clinical decline. These findings suggest that the CAG repeat length may influence or trigger the onset of HD, but other genetic, neurobiological, or environmental factors contribute to the progression of illness and the underlying pace of neuronal degeneration.

Adolescent↗
PubMed1993

Utilization patterns of total parenteral nutrition in a university hospital. A methodological approach.

To study the utilization of total parenteral nutrition, using methodology recommended by the World Health Organization, classification of components in accordance with the anatomical therapeutic chemical classification and defined daily dose system is necessary. Anatomical therapeutic chemical indices are available but defined daily dose values have not been established yet. In this article, a methodology to study both the total utilization of total parenteral nutrition, the utilization of individual substances and the composition of total parenteral nutrition is presented. To validate the proposed methodology, the utilization of total parenteral nutrition in a teaching hospital is studied, based on pharmacy computer data. The total utilization of total parenteral nutrition in the hospital in 1990 is 1.4 defined daily doses/100 bed-days. The composition of total parenteral nutrition varied greatly between the clusters. In this study we showed that utilization of total parenteral nutrition can be measured with the proposed methodology, using a defined daily dose for total parenteral nutrition in concurrence with a defined daily dose for the individual components.

Diet↗
PubMed1993

Thrombosis of a flexible coil coronary stent: frequency, predictors and clinical outcome.

OBJECTIVES: The aim of this study was to evaluate the predictors and clinical sequelae of stent thrombosis. BACKGROUND: Although coronary artery stenting is being increasingly applied, the major unique complication of stent thrombosis is not well characterized. METHODS: We studied 145 patients who underwent coronary artery stenting with the Gianturco-Roubin flexible coil design for abrupt vessel closure or to prevent restenosis. There were 17 stented vessel closures (11.7%), 7 as a result of acute (< 24 h) and 10 of subacute (days 1 to 21) thrombosis. RESULTS: In seven patients successful coronary recanalization was achieved with thrombolytic agents and balloon angioplasty. Creatine kinase was significantly elevated in 13 patients, with a Q wave myocardial infarction in 11 and emergency coronary artery bypass grafting in 8. Comparisons (multivariate analysis) with a control cohort (n = 33) of patients without thrombosis matched for age, gender and vessel stented revealed lesion eccentricity (p = 0.003), unstable angina (p = 0.048) and indication for stent implantation (abrupt closure versus restenosis) (p = 0.002), as predictors of thrombotic occlusion of stented vessels. Subtherapeutic anticoagulation (activated partial thromboplastin time < 2 times control value, prothrombin time < 1.4 control value) occurred at least once during the hospital stay in all 10 patients with subacute thrombosis and in 20 of 33 control patients (p = 0.047). In 2 patients with subacute thrombosis and 11 control subjects, subtherapeutic anticoagulation was necessitated by bleeding. CONCLUSIONS: Early thrombosis after coronary stenting was relatively common (> 10%), occurring predominantly in eccentric lesions and in patients with unstable angina pectoris. This complication is associated with significant adverse clinical outcomes and may be reduced by more intensive anticoagulation yet, in a delicate balance, can be precipitated by inadequate heparin therapy.

Angina, Unstable↗
PubMed1993

A quantitative assessment of limited joint mobility in patients with diabetes. Goniometric analysis of upper extremity passive range of motion.

OBJECTIVE: The syndrome of limited joint mobility is a common but not widely recognized musculoskeletal complication of diabetes. The purpose of this study was to further characterize this syndrome using quantitative goniometric measures. METHODS: Cross-sectional analysis of a sample population was performed to establish the prevalence, location, and severity of limited joint mobility and to determine its relationship to extraarticular manifestations and complications of diabetes. Passive range of motion of both upper extremities was measured by goniometry in 70 adult patients with insulin-dependent diabetes mellitus and 70 nondiabetic controls who were group-matched for age, sex, and general activity level. Joint mobility was assessed by both individual joint motions and a composite scoring technique. RESULTS: Analysis of individual joints and composite scores revealed significant differences between dominant and nondominant extremities in both the control and the diabetic groups. Diabetic patients were generally less flexible than nondiabetic subjects throughout the arm, especially in shoulder and finger joints. In the full study population, multivariate analysis revealed that advanced age, male sex, and the presence of diabetes were associated with decreased passive range of motion for a majority of joints (P < 0.05). In the diabetes group, passive range of motion was significantly correlated (P < 0.05) with age, sex, duration of diabetes, and to a variable extent, glucose control, but was not correlated with the presence of clinically significant neuropathy, retinopathy, nephropathy, or peripheral vascular disease, with activity level, or with hand dominance. Stepwise regression analysis failed to identify single key joint motion(s) to serve as possible screening tests in predicting generalized limited joint mobility of the upper extremity. Finally, the effect of limb usage on range of motion in flexion may differ in diabetic and nondiabetic subjects. CONCLUSION: Limited joint mobility is a generalized phenomenon occurring throughout the upper extremities of many diabetic patients. It is significantly related to age, sex, and to a variable extent duration of diabetes and glucose control. It is not related to the standard complications of diabetes as defined in this study.

Adult↗
PubMed1989

Complex coronary angioplasty: use of a new microprobe balloon catheter.

Since the introduction of coronary angioplasty by Gruntzig et al. (Circulation [Suppl II] 56:84, 1977), a key determinant to overall success has been advancement in equipment technology. Major advances have been made in the availability of low-profile catheters in the last 5 years that have facilitated penetration of high-grade distal and complex lesions. The USCl probe TM catheter is an example of a low-profile catheter that has shown favorable applicability in dilating high-grade stenoses. Preliminary data indicate that this device has good trackability and an extremely low profile, which allows penetration of stenoses where other current low-profile catheters have failed.

Angina Pectoris↗
PubMed1988

Vein of Galen aneurysm associated with dural AVM and straight sinus thrombosis. Case report.

A 64-year-old man presented with symptoms of obstructive hydrocephalus secondary to a vein of Galen aneurysm associated with a dural arteriovenous malformation and straight sinus thrombosis. The interrelationship of these lesions and their clinical and radiological features are discussed. It is proposed that in this case sinus thrombosis was the primary event in the subsequent development of the other lesions.

Arteriovenous Malformations↗
PubMed1987

Responses to converting-enzyme inhibition and hemorrhage in newborn lambs and adult sheep.

We compared the cardiovascular and hormonal responses to angiotensin converting enzyme inhibition and hemorrhage of 20% of blood volume in chronically instrumented unanesthetized newborn lambs and adult sheep. Administration of the nonsulfhydryl-containing converting-enzyme inhibitor enalapril reduced mean arterial pressure in the newborn but not in the adult animals. Blood pressure fell in both age groups after hemorrhage, and the hemorrhage-induced fall in blood pressure, integrated over the period of hypovolemia, was more pronounced when converting-enzyme inhibition was present in the lambs. This was not observed in the adults. Cardiac output fell following hemorrhage in both age groups, and the fall was greater when enalapril was present in the lambs, but this was not the case in the adults. Hemorrhage increased plasma renin activity in both groups, and enalapril augmented this increase. Plasma concentrations of vasopressin and catecholamines increased following hemorrhage within and between groups. Taken together these data suggest that the renin-angiotensin system plays a more important role in the maintenance of cardiovascular homeostasis in newborn lambs than it does in adult sheep, and catecholamine and vasopressin responses to volume loss can occur in the presence of blockade of the renin-angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗