Comparison of colour Doppler imaging with conventional duplex scanning in the evaluation of extracranial carotid stenosis.

OBJECTIVE: To assess the concordance between conventional duplex scanning and colour Doppler imaging in the grading of extracranial carotid artery stenosis. PATIENTS AND METHOD: A total of 67 carotid bifurcations in 48 patients were studied independently by two observers. First, each observer obtained a conventional duplex scan and recorded peak systolic and diastolic velocities. Then, each observer performed a colour Doppler study in which only the point of maximal colour shift was sampled. The stenosis in each case was subsequently classified, first as one of four classes (mild, moderate, severe or critical) on the basis of percent stenosis and peak systolic and diastolic velocities, and then as one of two groups (less than 70% or 70% or greater, with a peak systolic velocity of 2.3 m/second as the cut-off point). RESULTS: For the first observer, the two methods disagreed in 10 (15%) of the 67 cases. In five of these cases, colour Doppler imaging indicated a higher class of stenosis, and in the other five cases conventional duplex scanning indicated a higher class of stenosis. For this observer, the mean of the difference between conventional duplex and colour Doppler scanning for peak systolic and diastolic values was not statistically different from 0 (three-way analysis of variance). With colour Doppler imaging observer 1 detected all of the 14 cases of stenosis of 70% or greater that were detected by conventional duplex scanning. For observer 2, the results of the two methods differed in 12 (18%) of the 67 cases. For all 12 cases, conventional duplex scanning indicated a higher class of stenosis. The mean of the difference between the two methods was -23.8 cm/second (standard deviation 46.0) for peak systolic velocity and -10.7 cm/second (standard deviation 24.7) for peak diastolic velocity (both significantly different from 0). With colour Doppler imaging observer 2 did not identify 3 of the 16 cases of stenosis of 70% or greater that were detected by conventional duplex scanning. CONCLUSION: Discrepancies may exist between conventional duplex scanning and colour Doppler imaging in assessing extracranial carotid artery stenosis.

Postdischarge utilization of medical services by high-risk infants: experience in a large managed care organization.

BACKGROUND: Infants discharged from intensive care nurseries are a high-risk infant (HRI) population known to have increased utilization of medical services. Most studies tracking HRIs have been based on data obtained from individual chart review or direct patient contact. Given the high cost of such studies, it is desirable to develop less costly methods to track such infants. OBJECTIVES: Our goals were: (1) to identify an HRI cohort at two neonatal intensive care units; (2) to identify a control group of infants not meeting HRI criteria; and (3) to measure outpatient and inpatient utilization in both controls using computerized files in a managed care organization. METHODS: Using California Children's Services criteria as our starting point, we established an HRI definition. From a 1-year birth cohort of 7579 infants at two facilities, we identified 250 infants meeting the HRI definition at two neonatal intensive care units during 1990. We then matched the HRIs with a cohort of 896 randomly selected control newborns (those not meeting the HRI definition). Using organizational computer files and state of California death certificate tapes, we followed these infants until February 28, 1992. We measured the number of hospitalizations, total number of hospital days, and total number of outpatient visits and expressed these outcomes as rates per person-year. We also measured postdischarge mortality. RESULTS: The rate of hospitalization in the HRI group was 6.07 times (95% confidence interval [CI], 4.74-7.77) that in the control group. The utilization of hospital days by the HRI population (hospital days per 1000 person-months) was 13.24 times higher (95% CI, 11.00-16.04). The outpatient visit rate was 1.40 times higher (95% CI, 1.36-1.45) in the HRI population. CONCLUSION: Our findings in a large managed care organization corroborate previous studies showing that hospitalization rates are significantly higher among HRIs. In our study population, outpatient utilization was significantly higher as well. Our study also demonstrates the feasibility of using computerized files to study outcomes in selected pediatric populations. These methods can be used for epidemiologic studies, interventional trials, and planning for resource allocation.

Evidence for a DIOA-sensitive [K+,Cl-]-cotransport system in cultured vascular smooth muscle cells.

The existence of a [K+,Cl-]-cotransport system in vascular smooth muscle cells was investigated in the A10 cell line by studying the effect of DIOA (dihydroindenyl-oxy-alkanoic acid, a potent inhibitor) on K+, Rb+ and Cl- fluxes. Hypotonic medium (150 mOsm) increased initial rates of ouabain and bumetanide-resistant (OBR) Rb+ uptake by 100%, bumetanide and DIDS-resistant Cl- uptake by 200%, and OBR net K+ efflux by 130%. DIOA inhibited 40 to 100% of the Rb+ influx and net K+ efflux stimulation with an IC50 of 4 X 10(-5) mol/L. DIOA-sensitive Rb+ influx was a sigmoidal function of the decrease in osmolarity, with a threshold at about 230 mOsm. Our results suggest that vascular smooth muscle cells have a DIOA-sensitive [K+,Cl-]-cotransport system. Dissipation of the outwardly directed Cl- gradient with an apparent [Cl- to K+] stoichiometry much higher than one may provide the energy to ensure net KCl (and osmotic water) extrusion and cell volume regulation in these cells.

Stimulatory action of endothelin-1 on membrane Na+ transport in vascular smooth muscle cells in culture.

Endothelin-1 was able to induce an immediate and transient increase in cytosolic free Ca2+ concentrations in the A10 cell line of vascular smooth muscle. This was associated with a strong stimulation of the Na+:H+ exchange, the Na+, K+ pump and the [Na+,K+,Cl-]-cotransport system. Pump stimulation appeared to be secondary to sodium entry through Na+:H+ exchange because it was absent in Na+ loaded cells and in the presence of ethyl-isopropyl-amiloride. Cotransport stimulation was blocked by indomethacin, suggesting the involvement of a cyclooxygenase product. In conclusion, the monovalent ionic perturbations associated to the vasoconstrictor and mitogenic actions of endothelin-1 are counterbalanced by activation of the Na+,K+ pump and the [Na+,K+,Cl-]-cotransport system.

A mechanical stress increases sodium ion content in vascular smooth muscle cells through a calcium-dependent pathway: prevention by cicletanine via a cyclo-oxygenase product.

The non-laminar (rather turbulent) flow induced by cell washings was able to reversibly increase the sodium ion (Na+) content in cultured A10 aortic smooth muscle cells. Similar changes, although to a lesser extent, were observed in cardiocytes but not in fibroblasts, erythrocytes, thymocytes or macrophages, suggesting that the changes are specific to excitable cells. The increase in vascular sodium content had the following properties: (1) It was inhibited by nitrendipine; (2) it was accompanied by an increase in the free cytosolic Ca2+ content; (3) it was unable to stimulate the sodium pump; and (4) it reflected the qualitative and quantitative composition of the incubation media. These observations suggested that a non-laminar flow is able to open potential-dependent calcium channels, with secondary internalization of high amounts of extracellular ions. These ionic perturbations were blocked by low concentrations of cicletanine; the half-maximal inhibitory concentration (IC50) was about 10(-9) mol/l on internal sodium. The protective effects of cicletanine were inhibited by indomethacin, suggesting that they are mediated by a cyclooxygenase metabolite, perhaps prostacyclin. Captopril and diuretic drugs such as hydrochlorothiazide, furosemide, spironolactone or acetazolamide were unable to protect vascular cells against the harmful effects of cell washings.

[Ionic perturbations produced by a non-laminar flow in vascular smooth muscle cells in culture. Protection by cicletanine via a cyclo-oxygenase metabolite]. / Perturbations ioniques produites par un flux non laminaire dans les cellules musculaires lisses vasculaires en culture. Protection exercée par le ciclétanine via un métabolite de la cyclo-oxygénase.

The non-laminar (rather turbulent) flow, induced by cell washings was able to reversibly increase internal Na+ contents in cultured aortic smooth muscle (A10 cells). Similar changes (although to a lesser extent) were observed in cardiocytes but not in fibroblasts, erythrocytes, thymocytes or macrophages, suggesting that they are specific for excitable cells. The increased vascular sodium content had the following properties: it was inhibited by nitrendipine; it was accompanied by an increase in free cytosolic Ca2 contents; it was unable to stimulate the sodium pump and (iv) it reflected the qualitative and quantitative composition of the incubation media. These observations suggested to us that the increased vascular sodium content results from the opening of potential-dependent calcium channels with secondary internalisation of high amounts of extracellular ions. The ionic perturbations were blocked by low concentrations of cicletanine (IC50 of about 10(-9) M on intracellular sodium). Moreover, the protective effects of cicletanine were inhibited by indomethacin, suggesting that they are mediated by a cyclo-oxygenase metabolite, perhaps prostacyclin. Sodium nitroprusside, a compound able to stimulate calcium entry in the sarcoplasmic reticulum via cyclic GMP, was also able to protect vascular cells (although it acted at higher concentrations than cicletanine). Conversely, captopril and diuretic drugs such as hydrochlorothiazide, furosemide, spironolactone and acetazolamide were unable to protect vascular cells against the deleterious effects of cell washings.

Cholesterol microlithiasis: bacteriology, gallbladder bile and stone composition.

It is not known whether microcalculi possess structural differences compared with larger stones or whether they represent simply an earlier stage in stone disease. We carried out a controlled study on 10 patients affected by gallbladder cholesterol microlithiasis (CM). In all patients, samples from all parts of the stones were studied by X-ray diffraction and by infrared spectrophotometry. Bile analysis was carried out to determine cholesterol, phospholipid and total bile acid content. The cholesterol saturation indices (C.S.I.) were calculated. In all samples, bacterial bile culture was carried out. The results were compared with those of 10 patients who had undergone cholecystectomy for large cholesterol stones, and for 10 patients who had undergone abdominal surgery but without biliary pathology. Patients in these latter groups were matched with the first according to sex and age. Microcalculi proved to be layered (nucleus and external layer) in only 2 cases and larger stones in 9; cholesterol was seen to be the principal crystalline component in all cases. Traces of bilirubin were found in 7 CM and in the nuclei of 5 larger stones. These results show that the structural composition of microcalculi is similar to that of the nucleus of larger stones. No substantial differences exist, however, between the two groups of patients regarding the other parameters taken into consideration.

Affinity chromatography of a sequence-specific DNA binding protein using Teflon-linked oligonucleotides.

An affinity matrix was constructed by synthesis of a DNA oligonucleotide on a Teflon fiber support followed by deblocking and hybridization of the complementary strand. It was used to purify a sequence-specific binding protein at least 100-fold to near homogeneity. This matrix is easily fabricated on an automated DNA synthesizer, contains high levels of attached DNA, and has superior mechanical properties. It should be generally useful for affinity chromatography of DNA binding proteins.

Hemorrhage and anticoagulation after nonseptic embolic brain infarction.

Among 54 consecutive patients with acute nonseptic embolic brain infarction, there was CT evidence of hemorrhagic infarction in 1 patient (2%). None had clinical or CT evidence of massive brain hemorrhage even when anticoagulation therapy was used immediately. Seven patients (13%) had recurrent brain emboli, all within 7 days of the initial stroke. None of these patients was adequately anticoagulated at the time of recurrence. Immediate anticoagulation therapy should be employed after nonseptic embolic brain infarction if CT does not show hemorrhage and there is a persistent cardiac source of emboli.

Dystrophic axons and spinal cord demyelination in cystic fibrosis.

Neuropathologic changes in patients with cystic fibrosis include dystrophic axons in the nucleus gracilis and demyelination of the fasciculus gracilis. We reviewed 43 autopsy cases of cystic fibrosis to determine the incidence and severity of these changes. Sixty-six percent of patients developed dystrophic axons. There was a direct correlation between severity of neuroaxonal dystrophy and duration of disease. Demyelination of the fasciculus gracilis occurred in 11%. The neuropathology of cystic fibrosis resembles that of vitamin E deficiency in animals. However, vitamin E replacement failed to prevent neuropathologic changes in these patients.

Evidence for the parasexual cycle in a strain of Aspergillus flavus containing virus-like particles.

Eight isolates of A. flavus and A. parasiticus were screened for the presence of virus-like-particles (VLP). Only A. flavus strain NRRL 5565 contained detectable VLP. Spore color and auxotrophic mutants were induced in this strain and evidence for the parasexual cycle was obtained. Attempts to form heterokaryons between 3 auxotrophs of the VLP-containing strain and 9 auxotrophs from two different aflatoxigenic strains were unsuccessful.