Dynamic 3D-CT angiography.

BACKGROUND AND PURPOSE: 3D-CT angiography (3D-CTA), a vessel-cast technique, is useful in the diagnosis of patients with brain lesions and cerebrovascular disease. However, it provides no information on blood-flow dynamics. Therefore, we developed a new technique, dynamic 3D-CTA (d3D-CTA), that yields 3D images of the vasculature and allows assessment of the hemodynamics and of the cerebral perfusion. METHODS: We subjected 12 patients to d3D-CTA; 7 had brain tumors, 4 had arteriovenous malformations (AVMs), and 1 presented with cervical internal carotid artery occlusion. d3D-CTA was performed with a multidetector-row CT scanner with 64 detectors; the parameters were 0.5-mm section thickness, 0.5 seconds per rotation, 135 kV, and 150 mA. Contrast medium (total volume, 30-35 mL) was injected at 6-7 mL/s; scanning was started after a 5-second delay. Scans were generated with volume-rendering reconstruction and displayed in cine mode. RESULTS: We succeeded in obtaining d3D-CTA scans in all cases. The scans yielded 3D information on the vascular structures and hemodynamics and on the status of the cerebral perfusion. CONCLUSION: d3D-CTA facilitates the acquisition of information on the vascular and cerebral dynamic blood flow on 3D-CTA images. Despite the relatively high radiation exposure and contrast injection speed and its limited scan range, this technique is useful for the diagnosis of patients with brain tumors or cerebrovascular disease and for treatment planning.

Spinal evoked potentials following transcranial magnetic stimulation.

Motor evoked potentials by magnetic stimulation is less invasive and causes no pain as opposed to high current electric stimulation. However, the distribution of the magnetic field generated by the round coil has not been fully studied. In this report, we mapped the extent of the magnetic induction flux density, and then the evoked potentials from the spinal cord were investigated by transcranial magnetic stimulation. We also examined the origin of the evoked potentials obtained by the magnetic stimulation. The following results were obtained. The magnetic induction flux density was at its maximum at the edge of the coil. The potentials consisted of a first negative wave and subsequent multiphasic waves. The first negative wave was similar to a response of the subcorticospinal tract in the lower brain stem, while the subsequent multiphasic waves were similar to those of the pyramidal tract. Although magnetic stimulation has certain advantages over electric stimulation, several problems remain to be solved for the monitoring of motor functions in the clinical settings.

All-solid-state, high-power, deep-UV laser system based on cascaded sum-frequency mixing in CsLiB6O10 crystals.

We report on an efficient use of CsLiB6O10 (CLBO) crystals employed for an all-solid-state deep-UV laser system operated at 5 kHz. We obtained greater than 3 W of UV radiation around 242 nm by mixing the 349-nm third harmonic of a Nd:YLF laser with the tunable output from a Ti:sapphire laser in a CLBO crystal. This UV radiation was subsequently mixed with the residual 1047-nm output from the Nd:YLF laser in a second CLBO crystal. The system produced 1.5 W of deep-UV radiation at 196.3 nm, which is, to our knowledge, the highest deep-UV power below 200 nm generated in a nonlinear optical crystal. Additionally, the bandwidth of both outputs was estimated to be less than 200 MHz.

GABA increases refractoriness of adult rat dorsal column axons.

We applied randomized double pulse stimulation for assessing the effects of GABA and a GABAA antagonist on compound action potentials in dorsal column axons isolated from adult rat. We stimulated the axons with double pulses at 0.2 Hz and randomly varied interpulse intervals between 3, 4, 5, 8, 10, 20, 30, 50 and 80 ms. Action potentials were measured using glass micropipettes. The first pulse was used to condition the response activated by the second test pulse. Concentrations of GABA of 1 mM, 100 microM and 10 microM did not affect action potential amplitudes or latencies activated by conditioning pulses. In the control studies, before drug administration, test pulses induced response amplitudes that were significantly decreased at 3-, 4- and 5-ms interpulse intervals. The test action potential amplitudes were 84.6 +/- 2.5%, 89.0 +/- 3.9% and 93.3 +/- 3.6% (mean +/- S.E.M.) of conditioning pulse levels, respectively. At 3-ms interpulse intervals, test response latencies were prolonged to 104.3 +/- 1.0%, but were unchanged at the other interpulse intervals. The 10 microM, 100 microM and 1 mM concentrations of GABA affected test response amplitudes. Application of 100 microM GABA reduced the amplitudes of test responses at 3-, 4-, 5- and 8-ms interpulse intervals, to 59.2 +/- 3.0%, 70.0 +/- 3.0%, 80.2 +/- 1.1% and 88.6 +/- 3.6% of the conditioning pulse amplitudes, respectively. At both 100 microM and 1 mM concentrations, GABA significantly prolonged the latencies of test responses. Treatment with 100 microM GABA prolonged the latencies of test responses at 3-, 4- and 5-ms interpulse intervals, to 119.3 +/- 3.1%, 107.3 +/- 2.8% and 105.5 +/- 2.5% of conditioning pulse latencies, respectively. The addition of 100 microM bicuculline methochloride, a GABAA antagonist, eliminated the effects of 100 microM GABA. The combined application of GABA and bicuculline (both 100 microM) did not affect amplitudes or latencies of test responses. These results suggest that GABA(A) receptor subtypes are present on the spinal dorsal column axons of adult rat, and that they modulate the excitability of the axons. The randomized double pulse methods reveal that GABA increases refractoriness of adult rat dorsal column axons.

Evidence for serotonin sensitivity of adult rat spinal axons: studies using randomized double pulse stimulation.

We have recently shown both inhibitory and excitatory effects of serotonin on neonatal rat dorsal column axons. While neonatal rat dorsal column axons also respond to norepinephrine and GABA, adult rat dorsal columns are insensitive to the actions of both compounds. Therefore, we studied the effects of serotonin agonists on adult rat dorsal column axons using randomized double pulse stimuli at 0.2 Hz with random interpulse intervals of 3, 4, 5, 8, 10, 20, 30, 50 and 80 ms. The serotonin(1A) agonist, 8-hydroxy-dipropylaminotetralin-hydrobromide (8-OH-DPAT), significantly modulated test response amplitudes at 3, 4, 5 and 8 ms interpulse intervals by 29.6+/-4.0%, 17.4+/-2.1%, 9.6+/-2.3%, and 12.4+/-2.2% of conditioning pulse amplitudes, respectively. The mean latencies at 3, 4 and 5 ms interpulse intervals increased by 17.0+/-5.1%, 8.6+/-2.1%, and 5.1+/-1.4%, respectively (P<0.05). However, neither 10 microM 8-OH-DPAT nor 100 microM serotonin hydrochloride affected the compound action potentials evoked by conditioning or test pulses. In contrast, treatment with 100 microM quipazine dimaleate (a serotonin(2A) agonist) decreased the refractory period. While the response amplitudes to a 3-ms double pulse were reduced by 11.0+/-1.5% during the control period, the test response fell to only 2.4+/-1.8% of the conditioning response amplitudes after exposure to 100 microM quipazine. 8-OH-DPAT decreased the amplitude, prolonged the latency and increased the refractory periods of compound action potentials in the adult rat dorsal column, although a high concentration of the agonist (100 microM) was required for these effects. In contrast, the serotonin(2A) agonist, quipazine, decreased refractory periods. These results suggest that both serotonin(1A) and serotonin(2A) receptor subtypes are present on adult spinal dorsal column axons. Further, these receptors have opposing effects on axonal excitability, despite the fact that their sensitivities are relatively low.

Axonal regeneration through an autogenous nerve bypass: an experimental study in the rat.

Neuroma-in-continuity can manifest itself not only as pain but also as incomplete return of motor and sensory nerve function. The mainstay of current treatment for peripheral neuromas employs neurolysis or segmental resection with interposition grafting. These techniques are complicated by the loss of the remaining conduction through intact fibers within the injured segment. Based on the recent finding that end-to-side neurorrhaphies demonstrate axonal growth, we studied the use of a nerve "bypass" graft as a possible alternative to neurolysis or segmental resection with interposition grafting. A sciatic nerve crush injury model was induced in the Sprague-Dawley rat by compression with a straight hemostat. Epineurial windows were created proximal and distal to the injury. An 8-mm segment of radial nerve was harvested and anastomosed to the sciatic nerve at the epineurial window sites proximal and distal to the compressed segment (bypass group). A sciatic nerve crush injury without bypass served as a control. Electrophysiological testing and gate studies were performed over an 8-week period. Sciatic nerves were then harvested en bloc and studied under transmission electron microscopy at 1250 times magnification. Myelinated and unmyelinated axon counts were obtained. Nerve conduction velocity in the bypass group was significantly faster than conduction velocity in the control group at 8 weeks (44.8 m per second vs. 36.4 m per second; p = 0.031). We found no difference in myelinated axon counts between the proximal and distal segments of the control sciatic nerve. In the experimental sciatic nerve, a 160% increase in the number of myelinated axons was noted in the distal segment. Significant axonal growth was noted in the bypass nerve segment itself. Gait analysis using the sciatic functional index revealed improved function of the bypass group compared to the control group, but this was not statistically significant. Nerve bypass may serve to augment peripheral axonal growth while avoiding further loss of the native nerve.

Independent depressive mechanisms of GABA and (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide on young rat spinal axons.

We compared the effect of GABA and the serotonin receptor agonist (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT) on compound action potential amplitudes, latency, and conduction velocity in the spinal cord isolated from young (eight to 13-day-old) Long-Evans hooded rats. Supramaximally activated conducting action potentials and extracellular K+ activity were recorded with microelectrodes from the cuneatus-gracilis fasciculi and corticospinal tract. In the cuneatus-gracilis fasciculi, 8-OH-DPAT (10(-4) M) significantly reduced response amplitudes by 26.1 +/- 10.3% (mean +/- S.D., P < 0.0001, paired t-test, n = 27) and increased latencies by 20.3 +/- 7.9% (P < 0.0001). GABA (10(-4) M) reduced/amplitudes by 31.7 +/- 15.0% (P < 0.0001, n = 28) and increased latencies by 6.1 +/- 5.4% (P < 0.0001). However, neither GABA nor 8-OH-DPAT significantly altered conduction velocities, suggesting that the latency shifts are due to changes in activation time and not conduction velocity. In cortical spinal tract, 8-OH-DPAT (10(-4) M) depressed response amplitudes by 18.9 +/- 9.6% (P < 0.05, n = 5), increased latencies by 23.3 +/- 7.2% (P < 0.0001), but reduced conduction velocities by 19.9 +/- 10.2%. GABA (10(-4) M) reduced amplitudes by 16.4 +/- 7.5% (P < 0.01, n = 5), increased latencies by 5.3 +/- 2.3% (P < 0.05), and did not change conduction velocities. Bicuculline or picrotoxin blocked the GABA effects but did not affect the 8-OH-DPAT effects on both tracts. The potassium channel blocker tetraethylammonium did not alter the 8-OH-DPAT effects. The Na+/K(+)-ATPase inhibitor ouabain (10(-6) M) markedly enhanced the depressive GABA effects from 27.9 +/- 12.0% to 49.4 +/- 24.5% (P < 0.01, n = 9), but had no effect on 8-OH-DPAT-mediated effects. These results suggest that GABA and serotonin agonists depress axonal excitability through different and independent mechanisms.

A histologically distinctive interstitial pneumonia induced by overexpression of the interleukin 6, transforming growth factor beta 1, or platelet-derived growth factor B gene.

Interstitial pneumonia is characterized by alveolitis with resulting fibrosis of the interstitium. To determine the relevance of humoral factors in the pathogenesis of interstitial pneumonia, we introduced expression vectors into Wistar rats via the trachea to locally overexpress humoral factors in the lungs. Human interleukin (IL) 6 and IL-6 receptor genes induced lymphocytic alveolitis without marked fibroblast proliferation. In contrast, overexpression of human transforming growth factor beta 1 or human platelet-derived growth factor B gene induced only mild or apparent cellular infiltration in the alveoli, respectively. However, both factors induced significant proliferation of fibroblasts and deposition of collagen fibrils. These histopathologic changes induced by the transforming growth factor beta 1 and platelet-derived growth factor B gene are partly akin to those changes seen in lung tissues from patients with pulmonary fibrosis and markedly contrast with the changes induced by overexpression of the IL-6 and IL-6 receptor genes that mimics lymphocytic interstitial pneumonia.

Expression of hepatitis C virus core protein as a fusion protein with maltose binding protein. Detection of anti-hepatitis C core antibody by western blot.

Putative hepatitis C virus core sequence was amplified from a serum sample positive for anti-C-100-3 and expressed in Escherichia coli. Approximately 62 kDa fusion protein with maltose binding protein containing 20 kDa hepatitis C core protein was obtained. The antibody to this protein was detected in 53 of 54 (98%) sera from hepatitis C virus ribonucleic acid-positive patients including 40 sera positive for anti-C-100-3 and 13 sera negative for anti-C-100-3. The antibody was also detected in all of 12 patients with acute hepatitis C showing the earlier detectability of the antibody than anti-C-100-3. Thus, the protein expressed from the amplified hepatitis C core sequence by the polymerase chain reaction would be useful for the diagnosis of hepatitis C.

[All-trans retinoic acid induced a complete remission in a case of refractory relapsed acute promyelocytic leukemia].

Forty five year old male suffering from relapsed acute promyelocytic leukemia (APL) was treated with all-trans retinoic acid (ATRA) and attained second complete remission (CR) without bone marrow hypoplasia. He was diagnosed as having APL in September 1989. The DCMP-85 regimen first induced CR in October, however the disease relapsed in September 1990. The DCMP-85 and and the MEC (MIT, ETOP, Ara-C) regimens were applied for re-induction without success. Then, 45 mg/m2/day ATRA was given orally from December 28, 1990. Laboratory data before ATRA treatment were as follows; 35.4% leukemic cells in the bone marrow, Hb 11.0 g/dl, Plt 130,000/microliters, WBC 5,100/microliters without leukemic cells, and no DIC was detected. During the treatment, his bone marrow was examined frequently. The bone marrow series showed no hypoplasia at any time and gradual reduction of leukemic cells with proliferation of mature granulocytes. CR was attained on January 21, 1991. DIC did not develop. Cytogenetic anomalies including t(14;17;15) (q24;q11.2;q22) reduced from 29/30 cells at relapse to 4/30 cells at the time of CR. Dryness of mouth and lips, irritation around eyes and the elevations of GOT, GPT and triglyceride level were seen as the side effects of ATRA, however they were tolerable.

Measurement of visual acuity with logarithmic charts: comparison between methods of threshold estimation.

The variability of the repetition of visual acuity measurements with a log MAR acuity chart with five optotypes in each row of acuity was studied in four groups of subjects. In three groups the threshold was calculated by probability of seeing curves, but the optotypes were read in different orders. For the fourth group the acuity was taken as the smallest row discriminated. Estimating the threshold by a probability of seeing curve did not improve the threshold's stability. Poorer acuity was detected when the optotypes were read vertically. It is suggested that clinical visual acuity charts are not suitable tools for generating data points to be fitted by probability of seeing curves.

Surgical correction of trachoma-related upper eyelid cicatricial entropion utilizing the Barbera-Carre technique.

Upper eyelid cicatricial entropion is commonly encountered as a sequela of inflammatory conditions. The surgical correction of this defect is often difficult and frequently unsuccessful. We have used the Barbera-Carre technique with good results in 20 patients with cicatricial entropion due to trachoma. We take this opportunity to present the surgical technique and our results.

Calcitonin gene related peptide stimulates adenylate cyclase activity in rat striated muscle.

Rat calcitonin gene related peptide (CGRP) and salmon calcitonin (CT) stimulated adenylate cyclase activity in a dose-dependent manner in the rat diaphragm and in the kidney. The ED50 value of rat CGRP was lower and that of salmon CT was higher in the diaphragm than in the kidney. These results suggest that CGRP stimulates adenylate cyclase activity in the striated muscle by reacting with sites distinct from the site in the kidney.

Undergraduate instruction in physical medicine and rehabilitation.

The New York Medical College core curriculum includes a 1-week compulsory course in rehabilitation medicine in the student's senior year. The most common disabilities seen in rehabilitation medicine are discussed. The presentations consist of didactic lectures and patient demonstrations. The program which has evolved over the past 10 years has proved to be successful and has gained recognition from the school and students alike. Instructors teach topics of special interest to them and in which they have particular expertise. A written examination is given at the end of the course. Students also complete an extensive questionnaire which attempts to evaluate the course, compare it with the other rotations, and point out any changes in their attitudes. Of the 103 students who responded to the questionnaire, 75 indicated they achieved a better understanding of physical disability after the coarse, and 32 reported an improved attitude toward disability and improved perception of the field of rehabilitation medicine. Earlier exposure could have influenced the student's choice of a specialty. We believe that we have been allocated adequate time for effective presentation of the basic principles in rehabilitation medicine. However, crucial to attracting young students into the field is rotation through rehabilitation medicine early in their medical training.

Cell kinetics of human squamous cell carcinomas in the oral cavity.

Cell proliferation characteristic of human malignant tumors has been related to the responses of tumors to various therapeutic means. The present study mainly concerns a routine method to measure cell kinetic parameters in human solid tumors. Proposed for this aim is the in vitro double labeling method under hyperbaric condition. For assessment of the method, two steps were taken. First cell cycle parameters were compared in a mouse squamous cell carcinoma between this in vitro method and the in vivo percent labeled mitoses methods. Second, the in vitro method was applied to eight cases of human squamous cell carcinomas. The results indicate that two sets of the cell cycle parameters of mouse squamous cell carcinoma measured by the two methods are in good agreement within an experimental error. DNA synthesis time, labeling index and cell cycle time of human squamous cell carcinoma varied among cases with a dispersion of 2- to 3-fold, that is, with ranges of 4.1-14.0 h, 14.3-28.7% and 21.2-52.9 /, respectively.