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Biomedical subjects

D Ulrich

Publications and source records attributed to D Ulrich.

At least 55 records · Page 3Linked to original sources
PubMed1994

Electronic structure of motoneurons in spinal cord slice cultures: a comparison of compartmental and equivalent cylinder models.

1. Voltage-clamp, current-clamp, and morphological data were obtained from visually identified motoneurons in organotypic cocultures of rat embryonic spinal cord, dorsal root ganglia, and skeletal muscle. The cells were injected with Biocytin during whole-cell patch-clamp recordings and stained with horseradish peroxidase. 2. The somata and dendritic trees of the cells were reconstructed with a semiautomatic reconstruction system. The motoneurons had a common multipolar shape. An elliptic soma gave rise to 3-9 stem dendrites with a mean diameter of 2.5 +/- 0.9 (SD) micron terminating in 24 +/- 7 dendritic endings. The mean total dendritic path length was 3,306 +/- 1,075 microns. The mean total membrane surface area was 15,594 +/- 10,404 microns 2 with a dendritic to somatic membrane surface area ratio of 3.4 +/- 1.4 (n = 7 cells). 3. The ratio between the sum of the diameters of the two daughter branches and the diameter of the parental branch each raised to the 3/2 power at all branch points was 1.3 +/- 0.28 (n = 8 cells). The dendritic trees of the cells tapered continuously from the soma to the distal ends. The mean normalized dendritic trunk parameter of all cells was 0.62 +/- 0.22. 4. The motoneurons had a mean input resistance RN of 498 +/- 374 M delta, a mean membrane time constant (tau m) of 22 +/- 4.6 ms, and a mean dendritic dominance (rho) of 2.7 +/- 0.86 (n = 5 cells). The mean electronic length (L) calculated from tau m and the slowest voltage-clamp time constant (tau VC1) was 0.7 +/- 0.04 (n = 7 cells). 5. The specific membrane capacitance (Cm) estimated from the charge of the capacitive current during a voltage step and the total membrane surface area was 1.08 +/- 0.3 microF/cm2 (n = 6 cells). 6. Compartmental computer models were constructed of individual cells. Experimental and simulated voltage transients were matched with Cm = 1 microF/cm2, a uniform membrane resistivity (Rm) = tau m/Cm and a cytosolic resistivity (Ri) of 308 +/- 39 omega.cm (n = 3 cells). 7. The mean electrotonic length of the dendritic paths was 0.83 +/- 0.2 (n = 5 cells). The mean input resistance at the dendritic terminals (RT) was 1,413 +/- 260 M omega. Synaptic conductances were applied at all distal dendritic compartments of the model cells. The resulting synaptic currents were calculated at the input site and at the soma. The mean transient current attenuation ratio was 4.7 +/- 1.7 under idealized voltage-clamp conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Miniature excitatory synaptic currents corrected for dendritic cable properties reveal quantal size and variance.

1. Non-NMDA (N-Methyl-D-aspartate) receptor mediated miniature excitatory synaptic currents (mEPSCs) were recorded from motoneurons in organotypic cultures of embryonic rat spinal cord. 2. Amplitude histograms of mEPSCs were unimodal and skewed toward larger events. The mean of the modes of the amplitude histograms was -18 pA with a maximal amplitude range of -4 to -160 pA for individual mEPSCs. 3. Current transients to a short voltage pulse were used to estimate the passive cable parameters of the motoneurons. The mean membrane time constant (tau) and the mean electrotonic length (L) were 20 and 0.96 ms, respectively. 4. The amplitudes of the mEPSCs were corrected for imperfect space and voltage clamp. The resulting amplitude histograms could be fitted by the sum of two Gaussian curves, revealing a mean quantal size of -48 pA with a coefficient of variation (cv) of 0.28. 5. Our data suggest that quantal size and its variance are masked by the cable properties of the neurons and that simultaneous release of elementary quanta occurs occasionally.

Animals↗
PubMed1990

No measurable increase in thymidine glycol or 8-hydroxydeoxyguanosine in liver DNA of rats treated with nafenopin or choline-devoid low-methionine diet.

Male rats were treated for 2 months with 1000 ppm nafenopin in the diet or for 4 or 7 days with a choline-devoid low-methionine diet. DNA was isolated from the livers and analyzed for the presence of cis-thymidine glycol-3'-phosphate (cis-dTGp) by 32P-postlabeling and for the level of 8-hydroxy-deoxyguanosine (8-OH-dG) by electrochemical detection (ECD). In no DNA sample was the level of cis-dTGp above the limit of detection of 1 modified thymidine per 10(6) nucleotides. With 8-OH-dG, a background level of this modification of 20 8-OH-dG per 10(6) nucleosides was found in liver DNA of control rats, which was not affected by either treatment. It is postulated for thymidine glycol that a potential increase was below the limit of detection or was rapidly repaired in vivo and that the steady-state level of endogenous 8-hydroxydeoxyguanosine appears not to be influenced by the treatments chosen.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1990

[Functional diagnosis in follow-up of temporal arteritis treatment].

Fourteen patients (28 eyes) suffering from histologically confirmed temporal arteritis were examined with oculo-oscillodynamography (OODG) according to Ulrich and Ulrich as well as with orbital dynamography (ODG) according to Hager. These examinations were performed before and during prednisolone treatment. When ocular and orbital vessels are involved, temporal arteritis will result in a strong reduction of the ocular and orbital pulse blood volumes. Ocular perfusion pressures may also be reduced. In all 28 eyes of the 14 patients, OODG showed the ocular pulse blood volumes to be significantly reduced, while with ODG the ocular pulse blood volumes appeared to be within the normal range in 50% of the cases. Therefore, OODG is more reliable than ODG in the diagnosis of temporal arteritis. When performed during prednisolone treatment, OODG is a very sensitive indicator of successful or unsuccessful therapy. OODG permits an early detection of relapses and helps to avoid their sequelae. Since OODG can be repeated as often as desired and can be performed within a short time, it is very suitable for controlling the management of temporal arteritis.

Aged↗
PubMed1988

[Temporal arteritis--diagnosis and therapeutic control].

33 patients suffering from temporal arteriitis (Morbus Horton) were investigated noninvasively by Oculo-Oscillo-Dynamography (OODG), Orbita-Dynamography (ODG) and Temporalis-Dynamography (TDG). The ocular, orbital and temporal oscillograms and oscillodynamograms revealed characteristic and unmistakable alterations; i.e., striking reduction of the pulse volumes and a decrease of the blood pressures in the respective circulatory regions as a result of a stenosing and occluding vascular process. The 3 methods yielded typical patterns of the occluding process, which led to the conclusion that in untreated persons the stenosing process of the arteritis cranialis tends to start in the vascular branches of the external carotid artery and subsequently includes branches of the internal carotid system, such as the ophthalmic artery. High doses of prednisolone resulted in reopening of the vessels that had been stenosed and occluded by arteritis, and in most cases restored normal circulation in the regions examined within several weeks or months. From the investigations made on 66 eyes of the 33 patients, the authors conclude that combined use of OODG, ODG, and TDG makes it possible to diagnose temporal arteritis with a high degree of certainty. In all 33 cases the disease was diagnosed with OODG, ODG and TDG and confirmed histologically. Since the OODG, ODG, TDG examinations are well tolerated by the patient and can be repeated at any time, it is suggested to employ them for the supervision of therapy as well to detect any possible relapse of the inflammatory occluding vascular process.

Dose-Response Relationship, Drug↗
PubMed1985

Effects of N-nitrosomorpholine and phenobarbital on UDP-glucuronyltransferase in putative preneoplastic foci of rat liver.

Effects of initiators and promoters of hepatocarcinogenesis on UDP-glucuronyltransferase and arylhydrocarbon hydroxylase were investigated in foci of altered hepatocytes. A single administration of N-nitrosomorpholine (75 mg/kg, 24 h after partial hepatectomy) was used for initiation and chronic administration of phenobarbital (0.1% in tap water) for promotion. Histological evidence indicated that ATPase-negative, gamma-glutamyltranspeptidase-positive, and UDP-glucuronyltransferase-positive foci were highly correlated. Based on this evidence ATPase-negative foci were used as a guide to monitor early lesions and to microdissect lyophilized foci and extra-focal tissue. It was found that treatment with N-nitrosomorpholine led to a permanent increase of UDP-glucuronyltransferase activity in foci tissue (3- to 5-fold, detected 180 and 330 days after initiation). In contrast, arylhydrocarbon hydroxylase activity was decreased by 50%. Administration of phenobarbital further increased UDP-glucuronyltransferase activity in focal tissue (up to 9-fold, compared with control liver). However, this further increase of enzyme activity by phenobarbital was reversible. The results suggest that (i) initiation by chemical carcinogens leads to permanent alterations of drug metabolizing enzymes, consistent with increased toxin-resistance of initiated hepatocytes, and (ii) chronic administration of phenobarbital markedly enhances gene expression of UDP-glucuronyltransferase in initiated hepatocytes.

Adenosine Triphosphatases↗
PubMed1984

A strategy, structure, human resource database: OASIS.

Traditionally, strategic planners and human resource professionals have taken separate approaches in their attempts to improve organization functioning. As a result, strategic planners lack important information that affects the implementation of their plans and human resource managers have little impact on the strategic direction of their organizations. The University of Michigan, Hay Associates, and The Strategic Planning Institute have come together in a new venture to build a multicompany database that links organization characteristics and human resource and strategic planning practices with data on company financial performance. The database will be used to make intercompany comparisons on significant organization variables and to identify those practices that lead to improved financial performance.

Data Collection↗
PubMedDate not supplied

Recurrence of isolated unilateral temporalis muscle hypertrophy: case report.

A case of isolated unilateral temporalis muscle hypertrophy of unknown cause is presented. It had been treated surgically 10 years previously. The histologic workup showed normal muscle tissue. A year before, the patient had reported a slowly enlarging mass in the right temporal region next to the eye. The recurrence of temporalis muscle hypertrophy was idiopathic. It was managed using a combination of surgical treatment and botulinum toxin A injection.

Female↗
PubMedDate not supplied

[Soft tissue reconstruction following total knee arthroplasty: treatment possibilities and retrospective analysis of plastic surgery therapy treatment possibilities].

AIM: We performed a retrospective analysis of patients with soft tissue defects following total knee arthroplasty and therapy. Furthermore, we described the possibilities of covering soft tissue defects following knee arthroplasty. METHOD: In 5 patients, soft tissue defects following knee arthroplasty were covered with medial M. gastrocneminus flaps. Localisation and size of the defect, microbiology, risk factors, and interval between arthroplasty and the occurrence of the soft tissue defect were retrospectively analysed. RESULTS: On average, defects occurred 9 weeks after prosthesis implantation. In all cases, the soft tissue defect developed in the area of the incision. In 3 cases, wound infection was diagnosed. Four patients exhibited factors associated with wound-healing failure. No prosthesis was lost. CONCLUSION: The gastrocneminus muscle flap provides good quality coverage with small donor site defect, permits early mobilisation, and allows for fast rehabilitation. The risk of flap loss is minimal. Early and adequate defect coverage can reduce both prosthesis loss and amputation rates.

Aged↗
PubMedDate not supplied

Using cooperative learning strategies.

Nurse educators are challenged to develop innovative teaching strategies that help students think critically and interact skillfully with others. The authors present the merits of cooperative learning and describe ways that nurse educators can teach essential content using this educational strategy.

Education, Nursing, Baccalaureate↗
PubMedDate not supplied

Tic Tac Test Ready.

Explore the source record for details and available documents.

Education, Nursing, Baccalaureate↗