Derivation of Power M-Mode Transcranial Doppler Criteria for Angiographic Proven MCA Occlusion

BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.     

Neuroprotection with felbamate: a 7- and 28-day study in transient forebrain ischemia in gerbils

The use of glutamate antagonists and GABA agonists may protect neurons from the effects of transient ischemia. Felbamate is a new antiepileptic drug with glutamate antagonist and GABA agonist properties, We tested the efficacy of felbamate in a gerbil model of transient forebrain ischemia. Damage assessment was done with silver staining at 7 and 28 days after 5 min of bilateral carotid occlusion, Cerebral cortex, hippocampus (CA1 and CA4), thalamus and striatum were evaluated on a 4-point scoring system, The animals sacrificed at 28 days were also tested in a water-maze task to assess recovery of function, The initial dose of felbamate (300 mg/kg) was given 30 min before the ischemic insult in one set of animals and 30 min after the insult in another set of animals. There were 8 animals tested per group (total: 48 animals). There was significant neuronal protection with the use of felbamate, both before and after ischemia in all regions of the brain. Protection was seen in animals sacrificed at 7 and 28 days, Protection was moderate when felbamate was used before ischemia. It was highly significant when felbamate was given 30 min after the insult. Behavioral studies however did not show any difference in the felbamate treated animals versus the saline treated controls. The structural protection with felbamate was very significant when used in the post-ischemic period. This window for protection merits further evaluation in relation to the clinical setting of stroke.     

Pulmonary diseases in patients infected with the human immunodeficiency virus in Zimbabwe, Central Africa

During the 11 month period up to 30 September 1987, 37 patients (26 male, 11 female, mean age 27 years) with respiratory symptoms who were human immunodeficiency virus (HIV) positive, were studied prospectively on 40 occasions to determine the cause of any pulmonary complications. HIV was heterosexually transmitted. Predominant symptoms were cough (89%), fever (89%), weight loss (83%), and dyspnoea (60%). Transnasal fibre-optic bronchoscopy (with bronchoalveolar lavage, bronchial brushings and transbronchial lung biopsies) was performed on 35 patients, twice on 3 patients. 'Tru-cut' lung biopsies were obtained from 2 patients who died before bronchoscopy. Pulmonary tuberculosis was the commonest disease, being found in one-third of the patients (12 of 37). Mycobacterium tuberculosis was cultured from 4; the remainder of the plates were contaminated. Pneumocystis carinii was present in 8 patients: as the sole pathogen in 3, with Streptococcus pneumoniae in 4, Staphylococcus aureus in 2, and one also had tuberculous lymphadenitis. Endobronchial Kaposi's sarcoma was seen in 6 of 7 patients with skin nodules. Bacterial pathogens isolated included Staph. aureus (5), S. pneumoniae (5), Klebsiella pneumoniae (2), Haemophilus influenzae (2), H. parainfluenzae (1) and Pseudomonas aeruginosa (1). Invading Aspergillus fumigatus was diagnosed by lung biopsy in one. No diagnosis was reached for 8 patients. It is concluded that in Central Africa pulmonary complications in AIDS patients are similar to those in Europe and North America but the incidence of different pathogens depends on the prevalence of pathogens in the community. M. tuberculosis is probably the commonest pathogen. This study has confirmed that P. carinii pneumonia does occur, but occurs less frequently.     

Transesophageal echocardiography in the detection of potential cardiac source of embolism in stroke patients

To compare the diagnostic yields of transesophageal and transthoracic echocardiography in the detection of potential cardiac sources of embolism, 63 patients (mean +/- SD age 63 +/- 15 [range 18-87] years) with transient ischemic attacks or stroke underwent both procedures. Transthoracic echocardiography revealed a potential cardiac source of embolism in 14% (nine) of the patients, all of whom had clinical evidence of heart disease. Transesophageal echocardiography revealed a potential cardiac source of embolism in 41% (26) of the patients; 27% (seven) of these patients had no clinical cardiovascular abnormalities. Abnormalities detected only by transesophageal echocardiography in the patients with unsuspected cardiac disease included atrial septal aneurysm in two, patent foramen ovale in two, left atrial appendage thrombus in one, and myxomatous mitral valve in two. The 26 patients with an identified cardiac source of embolism were older (67.5 versus 59.4 years, p = 0.04), more frequently in atrial fibrillation (62% [16] versus 8% [3], p less than 0.0001), had a larger left atrium (43 versus 37 mm, p = 0.01) and more commonly had left ventricular hypertrophy (62% [16] versus 32% [12], p less than 0.02) than the 37 patients in whom no cardiac source of embolism was identified. Thus, transesophageal echocardiography is more sensitive than transthoracic echocardiography in the detection of potential cardiac sources of embolism in patients with cerebral ischemic events.     

Tick infestations on Zebu cattle in western Kenya: host resistance to Rhipicephalus appendiculatus (Acari: Ixodidae)

Tick-susceptible Friesian steers were used as bait animals to assess the availability of adult Rhipicephalus appendiculatus Neumann on the pasture. Assuming that initial gross pickup rates of ticks by cattle were similar, the numbers of female ticks that attached and the numbers that subsequently fed to maturity on individual cattle were compared based on data obtained from bait animals. The proportion of successful attachments on high-resistance (HR) cattle (0.30) was significantly less than that on the low-resistance (LR) animals (0.51). Similarly, the proportion of attached ticks that fed to maturity also was significantly lower on HR animals (0.15) than on LR animals (0.33). Female survival was calculated as the product of these two parameters. On the HR cattle, female survival (0.05) was significantly less than on LR (0.18). About 12% of the cattle had low resistance, and up to 73% of the females survived on them. These animals were responsible for much of the tick multiplication in the field population.     

The effect of surface sugars on liposomes in immunopotentiation

The effect of surface sugars of liposomes on the immunological responses to entrapped antigen has been investigated. alpha-Mannose and beta-galactose were grafted on the surface of liposomes containing lysozyme by covalent coupling of p-aminophenyl-D-glycosides to phosphatidyl ethanolamine liposomes using glutaraldehyde. Subcutaneous administration of antigen entrapped in beta-galactose liposomes stimulated an antibody response comparable to that elicited by sugar-free neutral liposomes. However, alpha-mannose bearing liposomes with entrapped lysozyme elicited an immune response similar to that induced by lysozyme in saline. Based on these observations it is suggested that alpha-mannose liposomes, that are specifically recognized by macrophages, are taken up rapidly by receptor mediated endocytosis and that the entrapped antigen is then rapidly degraded, resulting in low antibody production.     

Mutation screening analysis of the retinoblastoma related gene RB2/p130 in sporadic ovarian cancer and head and neck squamous cell cancer.

AIMS: To investigate the involvement of the RB2/p130 gene in the pathogenesis of sporadic ovarian cancer in addition to head and neck squamous cell carcinoma (HNSCC). METHODS: Paired tumour and patient matched normal DNA samples from 43 sporadic ovarian tumours and 39 normal/tumour HNSCC DNA samples were screened. The mutation screen used polymerase chain reaction (PCR) amplification followed by single strand conformation polymorphism analysis and direct sequencing of the PCR products. Exons 19 and 20 (B domain) and exons 21 and 22 (C-terminus) were analysed for mutations. These exons were chosen because most of the point mutations in RB2/p130 are located in the C-terminal region and mutations in these exons have been identified previously in nasopharyngeal carcinomas and primary lung tumours. RESULTS: No abnormal band shifts were seen in the samples analysed, and no bands directly sequenced revealed the presence of mutations. CONCLUSIONS: Genetic alterations in the RB2/p130 gene (exons 19-22) are unlikely to be involved directly in the pathogenesis of sporadic ovarian cancer or HNSCC.