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Biomedical subjects

J Schmidt

Publications and source records attributed to J Schmidt.

At least 343 records · Page 19Linked to original sources
PubMed1996

Ectopic pregnancy: prospective study with improved diagnostic accuracy.

STUDY OBJECTIVE: To assess the utility of ultrasonography, quantitative serum beta-human chorionic gonadotropin (beta-hCG) level, history, and physical examination in the diagnosis of ectopic pregnancy (EP) in the emergency department. METHODS: We prospectively studied 481 consecutive pregnant patients who presented to an urban ED with first-trimester abdominal pain or vaginal bleeding. History, physical examination findings, quantitative beta-hCG values, sonography findings, surgical findings, and final diagnosis were collected after patient enrollment in the study. We assessed the proportions of pregnant patients experiencing pain or bleeding with EPs versus those with abnormal and normal intrauterine pregnancies (IUPs). RESULTS: Pregnant women with abdominal pain or vaginal bleeding received beta-hCG values; positive radioimmunoassays prompted ultrasonography; indeterminate ultrasonography findings resulted in admission. Thirteen percent of patients had confirmed EPs; 99.5% of patients discharged from the ED had documented IUPs. Transvaginal sonography in the ED established EP or IUP in 75%. For EP detection, sonography is 69% sensitive and 99% specific. Single beta-hCG levels are useful in predicting EP; a beta-hCG value of 1,000 mIU/mL or lower shows a fourfold higher risk of EP. History and physical examination do not reliably diagnose or rule out EP; of EP patients, 9% reported no pain and 36% lacked adnexal tenderness. CONCLUSION: To prevent delayed diagnosis of EP in urban centers, pregnant women with abdominal pain or vaginal bleeding require evaluation by transvaginal ultrasonography. Indeterminate ultrasonography findings necessitate further evaluation. A beta-hCG level of 1,000 mIU/mL or lower should heighten suspicion of EP.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed1996

Paramyosin isoforms of Schistosoma mansoni are phosphorylated and localized in a large variety of muscle types.

Paramyosin, although a widely distributed muscle component among invertebrates, has hitherto not clearly been shown to occur in the muscles of schistosomes. Instead, it has been reported to occur in the tegument. In the present study, a specific antibody reacting with each of 10 isoforms of paramyosin was used for light microscopical immunolocalization in sections of Schistosoma mansoni. Specimens were fixed by a new method to immobilize antigens with uranyl acetate-trehalose-methanol. In cercariae, schistosomula, and adults, the circular and longitudinal muscles of the body wall, the dorsoventral muscles and those surrounding the gut and the pharynx as well as the fast moving cross-striated muscles of the tail of cercariae intensely reacted with the antibody. However, neither immunohistologically nor on Western blots of isolated tegument, were indications found for the presence of paramyosin in the tegument. In vivo phosphorylation and binding of anti-phospho-tyrosine and anti-phospho-serine antibodies show phosphorylation of paramyosin which probably is responsible for the generation of the isoforms.

Animals↗
PubMed1996

Balance and strength training in older adults: intervention gains and Tai Chi maintenance.

OBJECTIVE: To determine the effect on balance and strength of 3 months of intensive balance and/or weight training followed by 6 months of low intensity Tai Chi training for maintenance of gains. DESIGN: Randomized control intervention. Four groups in 2 x 2 design: Control, Balance, Strength, Balance + Strength, using blinded testers. SETTING: Exercise and balance laboratory at University of Connecticut Health Center. PARTICIPANTS: Subjects were 110 healthy community dwellers (mean age 80) who were free of dementia, neurological disease, and serious cardiovascular or musculoskeletal conditions. INTERVENTIONS: Short-term training (3 months) occurred 3 times/week (45 minutes Balance and Strength, 90 minutes Balance + Strength). Balance training included equilibrium control exercises of firm and foam surfaces and center-of-pressure biofeedback. Strengthening consisted of lower extremity weight-lifting. All subjects than received long-term group Tai Chi instruction (6 months, 1 hour, 1 time/week). MEASUREMENTS: Losses of balance during Sensory Organization Testing (LOB), single stance time (SST), voluntary limits of stability (FBOS), summed isokinetic torque of eight lower extremity movements (ISOK), and usual gait velocity (GVU). RESULTS AND CONCLUSIONS: Balance training meaningfully improved all balance measures by restoring performance to a level analogous to an individual 3 to 10 years younger: LOB = -2.0 +/- 0.3 (adjusted paired differences, P < .005 ANOVA); SST = 7.0 +/- 1.2 sec; and FBOS = 9.0 +/- 2.0% of foot length (P < .05). Strengthening increased ISOK by 1.1 +/- 0.1 Nm kg-1 (P < .005). There was no interaction between balance and strength training. Significant gains persisted after 6 months of Tai Chi, although there was some decrement.

Aged↗
PubMed1996

Photoinactivation of the giant neuropil glial cells in the leech Hirudo medicinalis: effects on neuronal activity and synaptic transmission.

1. We studied the effects of photoinactivation of neuropil glial (NG) cells of the leech Hirudo medicinalis on neuronal activity and synaptic transmission. Each segmental ganglion contains two of these giant glial cells, which are electrically and dye coupled. 2. One of the two NG cells in an isolated segmental ganglion was filled with the dye Lucifer yellow (LY). Subsequent irradiation of the ganglion with laser light (440 nm) to photolyze LY caused irreversible depolarization of both NG cells. The NG cells that were filled with LY depolarized from -73 +/- 1.1 (SE) mV to -22 +/- 2.4 mV within 25 +/- 2.8 min of continuous irradiation (n = 22). The other NG cell, which was not directly filled with LY, depolarized with some delay. 3. Photoinactivation of the NG cells caused an irreversible depolarization of Retzius neurons and noxious (N) sensory cells by a mean of 14 mV (n = 36) and 9 mV (n = 24), respectively. In addition, the input resistance was reduced by 54% in Retzius cells and by 34% in N cells. Spikes could not be evoked in Retzius cells after the inactivation of the NG cells, either by intracellular current injection or by electrical nerve stimulation. Similarly, anterior pagoda neurons, annulus erector neurons, and the excitor neurons of the ventrolateral circular muscles became inexcitable. However, N cells, heart interneurons, and most of the heart motor neurons, touch cells, and pressure cells could still generate spontaneous or evoked action potentials. 4. Photoinactivation of the NG cells impaired the electrical connection between the two Retzius neurons. The electrical coupling was completely eliminated in six of eight cell pairs and reduced by 66% in two others. 5. Photoinactivation of the NG cells in the 3rd and 4th segmental ganglion caused a complete block of the chemical synapse between reciprocal inhibitory heart interneurons in these ganglia; the bursting rhythm either stopped or changed to a tonic activity, whereas inhibitory postsynaptic potentials could not be recorded in either heart interneuron anymore. 6. Laser irradiation alone had no effect on neuronal activity and synaptic transmission. Addition of glutathione (10 mM) and ascorbic acid (10 mM) to the saline to bind extracellular radicals that might be produced by the irradiation did not suppress the effects caused by photoinactivation of NG cells. 7. Elevation of bath K+ concentration to 12 mM, acidification of the saline to pH 5.5, and alkalinization to pH 8.5 for 6 min each did not mimick the effects on membrane properties of Retzius cells as produced by inactivation of NG cells. The results suggest some role of glial cells in the maintenance of neuronal activity and electrical and chemical synaptic transmission.

Animals↗
PubMed1996

The value of nifedipine in the treatment of hypertension, coronary heart disease and myocardial infarction (post-infarction therapy).

Calcium antagonists are among the drugs most often prescribed in the treatment of cardiovascular diseases. Among the 2000 preparations most often prescribed in Germany in 1994, there were 48 calcium antagonists which presented a prescription rate of 1268 million defined daily doses. Calcium antagonists of the nifedipine type are by far the most often prescribed preparations of this group. They are targeted mainly against hypertension and coronary heart disease, with post-infarction angina pectoris also featuring among their indications. Recent publications have, in consideration of indications on possible risks associated with nifedipine medication, fanned discussions on the pros and cons of nifedipine medication and thus the value of calcium antagonists in treating hypertension and CHD as well as post-infarction patients. The purpose of this report is to analyze the current situation and to draw conclusions for the practical use of calcium antagonists.

Adult↗
PubMed1996

Membrane responses evoked by organic buffers in identified leech neurones

Using single-electrode current-clamp and two-electrode voltage-clamp, different identified neurones of the leech (Hirudo medicinalis L.) were shown to hyperpolarize, or to exhibit outward currents (usually >2 nA), during bath application of the organic buffers Mops, Pipes and Mes (10 mmol l-1). Tris and Hepes had little or no effect on the membrane properties of neurones when they were added to a bathing saline buffered by CO2-HCO3- at a constant pH of 7.4. Outward currents evoked by buffers obtained from two suppliers, Roth and Sigma, were not significantly different, except in the case of Pipes. Steady-state currents evoked by Pipes supplied by Roth were eightfold larger than steady-state currents evoked by Pipes from Sigma. A transient current peak always present in responses evoked by Pipes from Roth was never present in responses evoked by Pipes from Sigma. Outward currents evoked by buffers were due to a conductance increase and appeared to be carried by Cl-. In low-Cl- saline, hyperpolarizations evoked by Mops in Retzius cells were reduced. When Cl- was injected into heart motor neurones, the hyperpolarizations evoked by Mops reversed. Tetraethylammonium (TEA+) injected into heart interneurones did not block Mops-evoked hyperpolarizations. Mops-evoked outward currents in Retzius cells were partially blocked by d-tubocurarine and bicuculline methiodide, and the latter also partially blocked Mops-evoked hyperpolarizations in HE cells. Since d-tubocurarine partially blocked acetylcholine-evoked Cl- currents in Retzius cells and bicuculline methiodide partially blocked carbachol-evoked hyperpolarizations in HE cells, Mops appears to act on the cholinergic receptors of these neurones by mediating a Cl- conductance.

Journal Article↗
PubMed1996

A new variant of B1 elements, vB1, identified upstream of a retroviral integration site.

A new variant of the murine B1 retroposon family, vB1, was identified in antisense orientation 165 bases upstream of the integration site of RFB MuLV in infected NIH3T3 fibroblasts. vB1 revealed a characteristic B1 structure, but contained two additional unique repeats. This variant facilitates identification of related vB1 elements which are considered to represent a minor subgroup of B1 elements.

3T3 Cells↗
PubMed1996

Osteogenic potential of murine osteosarcoma cells: comparison of bone-specific gene expression in in vitro and in vivo conditions.

Bone tissue formation and the expression of osteoblast-specific genes were compared in vitro and in vivo for two well characterized murine clonal osteosarcoma cell lines (K7 and K8). In vitro studies were carried out under conditions that promoted extracellular matrix morphogenesis and mineralization. The K8 cells showed 8-fold greater alkaline phosphatase activity and mineral accumulation than did K7 cells during 21 days of in vitro growth. The K8 cell line showed high levels of bone sialoprotein (BSP), collagen type I (COL I), and alkaline phosphatase (APase) mRNA expression throughout its growth in vitro. In contrast, K7 cells showed an almost complete absence of BSP and COL I and very low levels of APase throughout the culture period. In vitro, both cell lines expressed very low levels of osteocalcin (OC). For in vivo studies, we used a three-dimensional culture device that permitted analysis of tissue formation by the cells after their implantation into syngeneic mice. The K8 cells consistently generated extensive mineralized woven bone after their subcutaneous implantation. The striking features distinguishing the bone formed by the implanted cells from normal recipient bone were the complete absence of osteoclasts or matrix resorption, the absence of OC protein, and very low levels of OC mRNA expression in the tissues formed by these cell lines. BSP, APase, and COL I expressions were maintained at high levels in the K8-produced tissues. In contrast to their near absence in vitro, APase, BSP, and COL I were expressed by K7 cells and increased with time in vivo. These findings demonstrate that the K7 cells in vitro are less differentiated than K8 cells, but that K7 cells in vivo undergo osteogenic maturation. Thus, expression of bone-specific genes in these osteogenic cell lines was dependent on systemic or local factors in recipient animals and was distinct for these cell lines when grown under in vitro conditions. OC protein does not appear to be needed for the mineralization of the extracellular matrix but may be needed to provide the necessary signals for the resorption and remodeling of the tissue.

Alkaline Phosphatase↗
PubMed1996

[Etiology and pathophysiology of acute pancreatitis].

The pathophysiology of acute pancreatitis can be divided into four different pathogenetic principles. 1. Ductular: The ductular pathogenesis is characterized by the frequent association between migrating gallstones and acute pancreatitis. The causative mechanism consists of an intraductal pressure and permeability increase with consecutive premature enzyme activation. 2. Acinar: The acinar pathogenesis is based on autoactivation of pancreatic enzymes after misdirected basolateral secretion into the interstitium of the pancreas and/or by colocalization of lysosomes and proenzyme-rich zymogen granules inside the acinar cell. 3. Mixed ductular-acinar: The main entity of this pathophysiological concept is the acute alcohol pancreatitis. An increase of intraductal pressure, of duct permeability and a possible direct toxic effect seem to be responsible. 4. Microcirculation disturbance: An impairment of pancreatic microcirculation appears to play a key role in the progression of edematous to necrotizing pancreatitis and was demonstrated in all models of necrotizing pancreatitis examined so far. Causative factors are poor blood fluidity by hemoconcentration, intravascular hypercoagulability, an impairment of arteriolar inflow by vasospasms, of capillary flow by direct endothelial injury and edema, of venous outflow by thrombosis, leukocyteendothelium interaction and direct toxic injury by activated enzymes, kinins and other mediators. A specific and therapeutically successful approach represents the administration of dextran which antagonizes both systemic and local causes of microcirculatory impairment.

Acute Disease↗
PubMed1996

[Use of the recurrence plot method in stochastic analysis of neuronal activity].

The recurrence plot method is described together with its application to the analysis of inner time relations in the sequences of interspike intervals. The depicted method was employed to analyze results from the computer model of the neuronal stochastic activity. It can be also used to analyze sequences of interspike intervals in the records from life neurons.

Action Potentials↗
PubMed1996

A model of stochastic activity of neurone in some types of Gaussian input processes.

A new approach to computer modelling of neuronal stochastic activity is described. The output dynamic activity which depends on the types and the number of input synapses, weights of the synaptic efficacy, the absolute refractory phase duration and threshold level is evaluated on this model in some types of Gaussian input processes. The behaviour of this model for one excitatory and one inhibitory synapse is described in dependence on the changes of excitation weight. The neuronal behaviour presented depends on the number of interspike intervals and the excitation weight and interspike interval density distribution. A novel concept of the e-curve is being introduced, which shows the dependence of the number of output interspike intervals on the weight of excitation on a stable inhibition level, the absolute refractory phase value and the threshold level. The properties of e-curves are discussed. Furthermore, examples of transformations of input stochastic processes are mentioned from the aspect of density distribution changes of interspike intervals.

Computer Simulation↗
PubMed1996

Little effect of tissue plasminogen activator in subretinal surgery for acute hemorrhage in age-related macular degeneration.

We studied the effect of intraoperative fibrinolysis prior to surgical evacuation of subretinal hemorrhage, which has been recommended as a valuable adjunct in the surgical treatment of submacular hemorrhage. We analyzed retrospectively the records of eight patients who underwent pars plana vitrectomy combined with subretinal injection of tissue plasminogen activator (TPA). The duration of symptoms ranged from 2 h to 14 days (median 1.5 days). During vitrectomy, TPA (6-75 micrograms) was injected subretinally through a retinotomy. After 20 min the liquified blood was surgically drained. The residual clot had to be extracted mechanically through an enlarged retinotomy site. In all patients, fibrinolysis was incomplete and an additional mechanical clot extraction was necessary. The postoperative visual acuity improved slightly in four patients, stabilized at the preoperative level in three patients, and worsened in one patient. During follow-up, one patient suffered from retinal detachment. In four patients a cataract developed. In all eyes, large defects of the retinal pigment epithelium resulted. In contrast to other authors, we did not find an acceptable liquefaction of the subretinal clot that would have facilitated surgical extraction of the hemorrhage. Therefore, a therapeutic benefit from the injection of TPA before removal of a subretinal hemorrhage was not distinct.

Acute Disease↗
PubMed1995

Chen et al. reply.

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Journal Article↗