Comparative susceptibility of Marek's disease cell lines to chicken infectious anemia virus.

Chicken infectious anemia virus (CIAV) is known to infect and replicate in various Marek's disease chicken cell lines (MDCCs) derived from Marek's disease (MD) tumors. One line, MDCC-MSB1, has been the substrate used in most studies. We compared a total of 26 MDCCs, including two sublines of MDCC-MSB1, MSB1 (L) and MSB1 (S), four other MD tumor-derived lines, and 20 lines derived from MD virus-induced local lesions, for susceptibility to the Cux-1 and CIA-1 strains of CIAV. The cell lines represented six phenotypic groups of T cells based on the expression of CD4, CD8, and TCR-2 and -3 surface markers. Susceptibility was measured by the number of cells positive for viral antigen in immunofluorescence (IF) tests at 3-10 days postinfection. No clear-cut differences were found in susceptibility related to phenotype, although CD4-/8+ lines and CD4-/8- lines might be more susceptible than CD4+/8- lines. However, several individual lines were more susceptible to Cux-1 than the two MSB1 sublines tested. Contrary to an earlier report, cells of MDCC-CU147, a CD8+, TCR3+, local-lesion derived line, were found to be susceptible to CIA-1. In fact, CU147 was distinguished by very high susceptibility to both CIAV strains. In direct comparisons with MSB1, CU147 detected approximately 10-fold lower doses of virus. Also, virus spread was faster (P < 0.05) in CU147 than in MSB1 and other lines. Results from polymerase chain reaction (PCR) tests to detect infection in titrations were in general agreement with IF test results although PCR detected infection in a few terminal dilution cultures that were negative by IF.

Failure of gamma-interferon to decrease mortality from group B streptococcal sepsis in neonatal rats.

Newborns possess an altered immune response to infection with impaired leukocyte chemotaxis and deficient production of gamma-interferon (IFN-gamma). IFN-gamma enhances neonatal leukocyte activation and movement. We proposed that IFN-gamma in conjunction with penicillin compared to penicillin therapy without IFN-gamma would increase survival from group B streptococcal sepsis in a neonatal rat model. Newborn rats were infected with 10(5) cfu of group B streptococci at 48-72 h of age and randomized to receive either serum albumin (controls), rat recombinant IFN-gamma, albumin and penicillin, or IFN-gamma and penicillin. Survival 120 h postinfection revealed: controls 5% (1/21); IFN-gamma 4% (1/24); penicillin 23% (5/22); and IFN-gamma plus penicillin 10% (2/21). Survival analysis with a lognormal parametric regression model revealed only the penicillin group to have improved survival compared to controls. Contrasting the penicillin group with the IFN-gamma plus penicillin group did not reveal a statistically significant difference by the Wald chi2 statistic (p = 0.25).

Size and duration of zidovudine benefit in 1003 HIV-infected patients: U.S. Army, Navy, and Air Force natural history data. Military Medical Consortium for Applied Retroviral Research.

OBJECTIVES: The study's objectives were to determine the size and duration of benefits of early versus delayed versus late treatment with zidovudine (ZDV) on disease progression and mortality in HIV-infected patients, and whether patients rapidly progressing before ZDV treatment had a different outcome from those not rapidly progressing before ZDV. DESIGN: The design was an inception cohort of 1003 HIV-infected patients. One hundred and seventy-four of the 1003 patients were treated before CD4 counts fell to <400 x 10(9)/L, ("early treatment"); 183 of 1003 patients were treated after CD4 counts fell to <400 x 10(9)/L but before clinical disease developed ("delayed treatment"); and 646 of the 1003 patients had either been treated after clinical disease developed or had not been treated at all by the end of follow-up ("late treatment"). Outcomes were progression to clinical HIV disease and mortality. RESULTS: The relative risk (RR) of progression for early versus delayed treatment was 0.58 (p < .03), and durability of ZDV benefits on progression was estimated at no more than 2.0 years; however, this estimate had wide confidence intervals. The RR of progression for delayed versus late treatment was 0.54 p < .0001, and durability of ZDV benefits was estimated at 1.74 years; this estimate had narrow confidence intervals. Survival was better for the early versus delayed treatment (RR = 0.55), but this difference was not statistically significant. In the subgroup of patients with more rapid CD4 decline prior to ZDV therapy, significant benefits on progression were observed for early versus delayed ZDV therapy (RR = 0.42, p = .02) and delayed versus late ZDV therapy (RR = 0.51; p = .0004). Duration of benefit was estimated to be 4.5 years (early versus delayed) and 1.7 years (delayed versus late). For patients with less rapid pre-ZDV decline in CD4 levels, a significant progression benefit was observed for delayed versus late therapy (RR = 0.50; p = .02). Duration of benefit in this subgroup was estimated to be 1.8 years. No significant benefit was found for early versus delayed treatment (RR = 1.12) in the less rapid pre-ZDV CD4 cell decline subgroup. CONCLUSIONS: Early treatment compared with delayed treatment was associated with a sizable reduction in HIV progression, but the duration of benefits was estimated to last only about 2 years. Delayed treatment compared with late treatment with ZDV was associated with substantial reduction of progression, but this reduction was also clearly limited in duration. Benefits on progression and mortality for the early treatment group were heavily dependent on the pre-ZDV CD4 slope. In the subgroup of patients with the most rapid pre-ZDV CD4 cell declines, the duration of benefit was much longer, possibly as long as 4 years.

Relationship between the immunosuppressive potential and the pathotype of Marek's disease virus isolates.

Isolates of Marek's disease virus (MDV) representing three pathotypes of differing virulence were compared for relative immunosuppressive properties in genetically susceptible P2a-strain and genetically resistant N2a-strain chickens. Criteria of immunosuppression were 1) persistence of early cytolytic infection (i.e., a delay or failure to enter latency) in lymphoid organs, 2) atrophy of the bursa of Fabricius and thymus as measured by organ weight proportional to body weight at 8 and 14 days postinfection (DPI), and 3) histopathologic evidence of necrosis and atrophy in lymphoid organs. No significant differences in infection level were observed among the pathotypes during the early (4-5 DPI) period of infection. However, the extent of persistent cytolytic infection at 7-8 DPI, based on numbers of tissues positive and mean scores in immunofluorescence tests, was greater (P < 0.05) for three isolates (RK1, 584A, 648A) in the highest virulence pathotype (very virulent-plus MDV [vv + MDV]) than for two isolates (JM16, GA5) in a lower virulence (virulent MDV [vMDV]) pathotype. Results from two isolates (RB1B, Md5) classified in the intermediate very virulent pathotype (very virulent MDV [vvMDV]) fell between those from the other two pathotypes. Similarly, there was a stepwise effect of viral pathotype in which the vv + MDV isolates caused the most severe damage to lymphoid organs in terms of atrophy (relative organ weights) and histopathologic changes. Organs from chickens infected with vv + MDVs showed little recovery between 8 and 14 DPI. The vMDV isolates caused the least severe damage, and lymphoid organs showed a significant return toward normal by 14 DPI; vvMDV isolates induced intermediate degrees of atrophy and recovery. The same pattern of relationship between virulence pathotype and degree of bursal and thymic atrophy was also observed in genetically resistant N2a chickens. These results suggest that the degree of immunosuppression is linked to virulence and that a simple measure of atrophic changes (relative organ weights) in the bursa of Fabricius and thymus might be useful in determining the pathotype classification of new MDV isolates. The basis for differences in immunosuppressive potential of MDV isolates needs further clarification.

Attempt to correlate urine arsenic excretion with clinical course during melarsoprol therapy of patients with Rhodesian trypanosomiasis.

This study enrolled 28 CNS-involved patients with Trypanosoma brucei rhodesiense at the Kenya Trypanosomiasis Research Institute (Alupe, Kenya) to examine treatment efficacy and toxicity of melarsoprol in relation to renal excretion/dose relationships. This study complied with World Health Organization treatment recommendations, initially treating with suramin followed by three courses of melarsoprol. Traced study patients had a relapse rate of 4.1%. The toxicity and crude death rate was 7.1%. Total urine arsenic output was measured between 24 and 48 hr after the last dose for each course. The range of means of total urine arsenic output between the three treatment courses was 356-511 micrograms. There was no correlation comparing melarsoprol dose, estimated creatine clearance, or urine arsenic output. Urinary pharmacokinetic parameters are not predictive of toxicity or therapeutic efficacy.

Management of arterial occlusive disease following radiation therapy.

Clinically significant arterial occlusive disease developed in 26 patients at between 5 months and 44 years (mean(s.d.) 10.7(12.0) years) following radiation therapy. Therapeutic radiation was associated with lesions of the carotid artery (nine patients), subclavian-axillary arteries (seven) and the abdominal aorta and its branches (10). Clinical presentations included transient ischemic attack, stroke, vertebrobasilar insufficiency, carotid bruit, upper- or lower-extremity ischemia and renovascular hypertension. Surgery for cerebrovascular insufficiency included carotid endarterectomy with vein patch, interposition grafting or subclavian-to-carotid bypass. Carotid or subclavian-to-axillary bypass was performed for upper-extremity ischemia. A combination of endarterectomy and Dacron or saphenous vein grafts was used for infrarenal reconstruction. Tunnels were placed orthotopically. Musculocutaneous flaps assisted in healing selected wounds. Ureteral catheters were useful adjuncts in abdominal vascular reconstructions. There were no operative deaths, strokes or amputations. One patient had recurrent transient ischemic attacks following subclavian-to-carotid bypass. The mean(s.d.) postoperative follow-up was 48.1(39.6) months. Patients presenting with end-organ ischemia following radiation therapy can be managed successfully with aggressive surgical revascularization using a broad spectrum of reconstructive techniques.

Comparison between adaptive search and bit allocation algorithms for image compression using vector quantization.

This article discusses bit allocation and adaptive search algorithms for mean-residual vector quantization (MRVQ) and multistage vector quantization (MSVQ). The adaptive search algorithm uses a buffer and a distortion threshold function to control the bit rate that is assigned to each input vector. It achieves a constant rate for the entire image but variable bit rate for each vector in the image. For a given codebook and several bit rates, we compare the performance between the optimal bit allocation and adaptive search algorithms. The results show that the performance of the adaptive search algorithm is only 0.20-0.53 dB worse than that of the optimal bit allocation algorithm, but the complexity of the adaptive search algorithm is much less than that of the optimal bit allocation algorithm.

Subclavian artery catheterization: a new approach for endovascular procedures.

PURPOSE: Percutaneous access to the arterial system for endovascular procedures is usually achieved through the femoral arteries. When femoral access is precluded, the axillary or brachial arteries serve as alternatives. Complications associated with the use of the latter arteries have led us to develop subclavian arterial catheterization. METHODS AND RESULTS: From 1978 to 1993, 569 patients underwent angiography via the subclavian artery (> 99% left subclavian artery); 134 were studies of the aortic arch and brachiocephalic vessels; 435 studies involved the descending and abdominal aorta and its branches and runoff. Coronary arteriography was also feasible. Since 1986, 44 patients have undergone endovascular procedures: 33 percutaneous transluminal angioplasties of the visceral, iliac, femoral, and popliteal arteries and 11 thrombolytic procedures of aortofemoral graft limbs (n = 3) and femoral distal bypasses (n = 8) were performed. Complications (1.2%) included partial pneumothorax (n = 2), hemorrhage requiring operative control (n = 2), causalgia (n = 1) and embolization (n = 2). CONCLUSIONS: Whenever percutaneous femoral catheterization cannot be achieved or an alternate access point is indicated, we select the subclavian approach as an alternative to axillary, brachial or translumbar access. It is safe, expeditious, and versatile for virtually all types of systemic and cardiac catheterization; it is also applicable to thrombolysis and balloon angioplasty.

Allograft vein bypass: is it an acceptable alternative for infrapopliteal revascularization?

PURPOSE: Autogenous vein bypass grafts to infrapopliteal outflow sites have patency and limb salvage rates significantly superior to those obtained with prosthetic grafts. However, when infrageniculate bypass is required for limb-threatening ischemia in the patient lacking suitable autogenous veins, nonautogenous reconstruction or primary amputation are the only other alternatives. METHODS: During a 2-year period we implanted 25 cryopreserved allograft saphenous vein bypass grafts in 24 patients (median age 76 years) with tissue necrosis (20 patients), rest pain (4 patients), or acute ischemia (1 patient); 16 patients were men and 8 were women. As many as six previous revascularizations were performed in 79%; two grafts extended to the infrageniculate popliteal artery; 23 grafts extended to a paramalleolar vessel. RESULTS: Secondary patency at 1 month was 87%, but only 36% at 1 year. Use of warfarin (Coumadin) failed to improve the patency rate (five of nine occlusions treated with Coumadin versus eight of 16 not treated with Coumadin). Only eight of 24 patients are alive with open grafts; nine patients have died. CONCLUSIONS: Unheralded occlusions more typical of prosthetic graft failure tempered the initial enthusiasm and effectiveness of vein allografts. All autogenous options must be exhausted to complete distal, secondary revascularization before resorting to nonautogenous conduits. Use of allograft veins must be viewed with continued skepticism.

Addition of droperidol to patient-controlled analgesia: effect on nausea and vomiting.

A double-blind trial of the effect of droperidol on the incidence of nausea and vomiting in patients using patient-controlled analgesia was carried out in 60 healthy women undergoing abdominal hysterectomy. After a standard anaesthetic including droperidol 2.5 mg as a prophylactic antiemetic, patients were randomly allocated to receive postoperative patient-controlled analgesia with either morphine alone (2 mg.ml-1) or morphine (2 mg.ml-1) with droperidol (0.2 mg.ml-1) added to the syringe. Verbal scores and visual analogue scores for nausea, vomiting, pain and sedation were made at 4, 12 and 24 h postoperatively, and any requirement for intramuscular prochlorperazine noted. There was no difference between the groups at any time in the amount of morphine consumed or in pain scores. At 12 h, patients receiving droperidol experienced significantly less nausea, and over the first 24 h, 31% required prochlorperazine compared with 59.3% of patients not receiving droperidol. The number of patients with sedation at 24 h was significantly greater in the droperidol group. We conclude that the addition of droperidol to morphine both reduces nausea and the need for further antiemetic treatment.

A comparison of several vector quantization codebook generation approaches.

A review and a performance comparison of several often-used vector quantization (VQ) codebook generation algorithms are presented. The codebook generation algorithms discussed include the Linde-Buzo-Gray (LBG) binary-splitting algorithm, the pairwise nearest-neighbor algorithm, the simulated annealing algorithm, and the fuzzy c-means clustering analysis algorithm. A new directed-search binary-splitting method which reduces the complexity of the LBG algorithm, is presented. Also, a new initial codebook selection method which can obtain a good initial codebook is presented. By using this initial codebook selection algorithm, the overall LBG codebook generation time can be reduced by a factor of 1.5-2.

Fast full search equivalent encoding algorithms for image compression using vector quantization.

Three fast search routines to be used in the encoding phase of vector quantization (VQ) image compression systems are presented. These routines, which are based on geometric considerations, provide the same results as an exhaustive (or full) search. Examples show that the proposed algorithms need only 3-20% of the number of mathematical operations required by a full search and fewer than 50% of the operations required by recently proposed alternatives.

Influence of masker bandwidth on binaural masking level differences.

Masking level differences (MLDs) were investigated using masking noise with 160 Hz (amplitude-modulated noise) and 600 Hz (filtered-random noise) bandwidth. One hundred normally hearing subjects received the MLD test under both types of noise. Significant differences between noise types were observed in both N0S pi and N pi S0 conditions; MLDs were larger in amplitude-modulated noise. Consideration of these differences would indicate that older MLD norms based solely on filtered-random noise are invalid for amplitude-modulated noise especially where bandwidth differences in the noise exist. Were the norms for 600-Hz-wide filtered-random noise to be applied to results of MLD testing performed using 160-Hz-wide amplitude-modulated noise, patients with lesions in the central auditory pathway might exhibit normal or borderline normal results. Clinical MLD norms established on one type of noise should not be used to interpret MLD results obtained using a different type of noise.

The response times during anaesthesia of pulse oximeters measuring oxygen saturations during hypoxaemic events.

Episodes of desaturation were recorded simultaneously by computer from two Ohmeda Biox 3700 pulse oximeters, one with an ear and one with a finger probe, on patients undergoing anaesthesia. Over a period of 6 months, 28 episodes of desaturation were detected. Analysis of the recordings showed the mean minimum saturations recorded for ear and finger probes were 86.3% and 83.5% respectively (p less than 0.01). The mean delay for finger compared to ear pulse oximetry was 4.4 s (p less than 0.01). Analysis at different saturation levels showed finger probe responses to be significantly slower than ear probe responses at saturations equal to and above 91% (p less than 0.05). At saturation levels of 90% or less no significant difference in probe response times were found.

Evidence that Clostridium perfringens theta-toxin induces colloid-osmotic lysis of erythrocytes.

Clostridium perfringens theta-toxin was shown to lyse target erythrocytes by a colloid-osmotic mechanism. Analysis showed the onset of lysis of erythrocytes by theta-toxin could be temporarily stabilized with 0.3 M sucrose. Flow cytometry analysis of the size distribution of theta-toxin-treated erythrocytes showed swelling of the erythrocytes prior to lysis.

Percutaneous transluminal angioplasty of the lower extremities by the vascular surgeon.

As vascular surgeons, we performed 376 percutaneous transluminal angioplasties as follows: aorta and iliac arteries (148), infrainguinal arteries (191), and bypass grafts (21). Sixteen procedures were attempted but not completed. Neodymium-yttrium-aluminum-garnet laser thermoprobe was successfully used prior to balloon dilatations in 49 procedures. In contrast to our experience with operative intervention, percutaneous transluminal angioplasty was performed more frequently for claudication (75%), nondiabetics (72%), and women (45%). Median age was 71 years. Percutaneous transluminal angioplasty either preceded or followed proximal or distal open reconstruction in 58 extremities. Primary patency rates for iliac percutaneous transluminal angioplasties were: 94% at one month, 93% at six months, and 88% at one year. For infrainguinal percutaneous transluminal angioplasties they were 95%, 82%, and 70% at 1, 6, and 12 months, respectively. Repeat percutaneous transluminal angioplasty increased the one-year patency rates to 92% and 86% for iliac and infrainguinal percutaneous transluminal angioplasties, respectively. Preliminary data indicate that the six-month secondary patency rates were 82% for laser-assisted percutaneous transluminal angioplasty and 65% for percutaneous transluminal angioplasty of distal bypass grafts. The implementation of balloon angioplasty was facilitated by our 21 years of experience with arteriography. Percutaneous transluminal angioplasty has become a valuable adjunct to the practice of vascular surgery by expanding the therapeutic options for managing peripheral vascular occlusive disease.

Isolation of a tryptic fragment from Clostridium perfringens theta-toxin that contains sites for membrane binding and self-aggregation.

Trypsin cleaves Clostridium perfringens theta-toxin (perfringolysin O or PFO) at a single site between residues 303 and 304 (Ohno-Iwashita, Y., Iwamoto, M., Mitsui, K., Kawasaki, H., and Ando, S. (1986) Biochemistry 25, 6048-6053; Tweten, R. K. (1988b) Infect. Immun. 56, 3228-3234) and yields an amino-terminal fragment of 30,208 Da (T1) and a carboxyl-terminal fragment of 22,268 Da (T2). Both peptides were purified by reverse phase chromatography of trypsin-nicked PFO. Neither peptide retained hemolytic activity. Peptide T1 had no apparent effect on the hemolytic activity of PFO, whereas T2 was found to inhibit the hemolytic activity of PFO and was analyzed further. The order of binding of T2 and PFO to membranes did not alter the inhibitory effect of T2 on PFO-induced hemolysis, indicating that competitive binding by T2 for PFO membrane binding sites was not the basis for the observed inhibition. Further analysis showed that T2 could inhibit membrane-dependent fluorescence energy transfer (FET) between PFO molecules labeled with fluorescein (fluorescent donor) or tetramethylrhodamine (fluorescent acceptor). This provided evidence that T2 could complex with PFO. T2 was also found to be incapable of self-aggregation (as opposed to PFO), since preincubation of T2 with either erythrocytes or erythrocyte ghost membranes did not affect the T2-dependent inhibition of hemolysis or FET. These data indicate that T2 inhibits PFO-dependent hemolysis by forming a complex with PFO, which inhibits aggregation and that the membrane binding site and a single aggregation site remain intact on T2.