Excitation functions of (alpha,xn) reactions on (nat)Rb and (nat)Sr from threshold up to 26 MeV: possibility of production of (87)Y, (88)Y and (89)Zr.

Excitation functions were measured by the stacked-foil technique for (nat)Rb(alpha,xn)(87m,87m+g,88)Y and (nat)Sr(alpha,xn)(86,88,89)Zr reactions from their respective thresholds up to 26 MeV. The samples for irradiation were prepared by sedimentation and pellet pressing techniques. The measured data were compared with those available in the literature. From the excitation functions, integral yields of the products were calculated. The suitable energy ranges for the production of (87)Y and (88)Y via (nat)Rb(alpha,xn) processes and of (89)Zr via the (nat)Sr(alpha,xn) process are E(alpha)=26-->20 MeV, E(alpha)=26-->5 MeV and E(alpha)=20-->8.5 MeV, respectively. The respective yields amount to 8.2, 0.08 and 0.9 MBq/microA h. Production of (88)Y is feasible if a waiting time of about 2 months is allowed to let the impurities decay out. Also, (87)Y can be produced with a relatively low impurity of (88)Y. The yields of both (88)Y and (87)Y via the present routes are, however, appreciably lower than those via the (nat)Sr(p,xn) processes. There is a possibility to produce (89)Zr via the alpha-particle irradiation of (nat)Sr. The yield is rather low but would be considerably increased if enriched (86)Sr would be used as target material. The radionuclidic impurity levels in all the three products are discussed.     

Usefulness of erythrocyte protoporphyrin as a primary screening test for lead exposure in children

Erythrocyte protoporphyrin and blood lead concentrations were measured in samples from 583 Saudi children attending the outpatient clinics. Erythrocyte protoporphyrin concentrations showed poor correlation with blood lead concentrations of 25 ug dl^?1 and below. Measurement of erythrocyte protoporphyrin as a primary test for lead exposure is not recommended.     

Clinical use of a standard kit-preparation of radiolabeled monoclonal antibody 96.5 in the diagnostic imaging of metastatic melanoma

We studied the efficiency of a standard-kit preparation using 1 mg 111In-labeled 96.5 monoclonal antibody in combination with 19 mg of unlabeled antibody in the diagnostic imaging of 27 patients with documented metastatic melanoma. Twenty-three of 26 patients (88%) demonstrated immunoscintigraphic localization of tumor. Of 104 metastatic sites previously documented by conventional studies, 62 (60%) were identified by immunoscintigraphy. A total of 77 sites demonstrated localization of radiolabeled antibody. Fifty-four (70%) corresponded to known sites of disease; eight sites (10%) were "discovered" by immunoscintigraphy and subsequently confirmed by conventional studies; 15 imaged sites (20%) could not be confirmed by conventional studies. Size and location of metastasis appear to be important features that influence imaging efficiency. Tumor size (greater than or equal to 2 cm v less than 2 cm) appears to be the statistical dominant determinant. The feasibility and potential clinical use of radioimmune imaging of tumors is discussed.     

Novel 5-flucytosine-resistant clade of Candida dubliniensis from Saudi Arabia and Egypt identified by Cd25 fingerprinting

DNA fingerprinting of Candida dubliniensis isolates using the species-specific probe Cd25 previously showed that this species consists of two distinct groups, termed Cd25 group I and Cd25 group II. The present study investigated the population structure of 30 C. dubliniensis oral isolates from Saudi Arabia and Egypt using Cd25 fingerprinting and rRNA gene internal transcribed spacer region-based genotyping. Cd25 fingerprinting analysis of these isolates revealed two distinct populations, the first of which consisted of 10 closely related genotype 1 isolates (average similarity coefficient [S(AB)] value, 0.86). The second population of 20 isolates was much more heterogeneous (average S(AB) value, 0.35) and consisted of two distinct subpopulations, one of which consisted of genotype 3 isolates (n = 13) and the other of genotype 4 isolates (n = 7). A mixed dendrogram generated from the fingerprint data from the 30 Saudi Arabian and Egyptian isolates, 5 Israeli isolates, and 51 previously characterized international isolates (32 of Cd25 group I and 19 of Cd25 group II) revealed the presence of three distinct main clades. The first corresponded to the previously described Cd25 group I and contained all the Saudi Arabian, Egyptian, and Israeli genotype 1 isolates mixed with international isolates. The second clade corresponded to the previously described Cd25 group II and contained three Israeli isolates, one genotype 2 isolate, one genotype 3 isolate, and a genotype 4 variant isolate, which were mixed with international isolates. The third clade has not been described before and consisted solely of the 20 Saudi Arabian and Egyptian genotype 3 and 4 isolates identified in this study and a previously described genotype 4 Israeli isolate. All 20 Cd25 group III isolates exhibited high-level resistance to 5-flucytosine (MIC > or = 128 microg/ml), whereas all Cd25 group I and Cd25 group II isolates tested (10 Saudi Arabian and Egyptian, 16 Israeli, and 24 international) were susceptible to 5-flucytosine (MIC < or = 0.125 microg/ml). The results of this study show for the first time the presence of a novel 5-flucytosine-resistant clade of C. dubliniensis (Cd25 group III) that is predominant among isolates from Saudi Arabia and Egypt and absent from a previously characterized international collection of 98 isolates from 15 countries.     

Usefulness and limitation of phylogenetic analysis for hepatitis C virus core region: application to isolates from Egyptian and Yemeni patients

Summary We report here the nucleotide sequences of the core region of HCV isolates from Egyptian and Yemeni patients and the method for classifying these HCV isolates by phylogenetic analysis. Sequence comparison suggested that the genotypes of these isolates were the same. Preliminary phylogenetic analysis of the HCV core region indicated that the genotypes of both isolates were 1c. However, an additional phylogenetic tree of the HCV core region constructed using a greater number of HCV isolates than that used in the preliminary analysis and on the basis of alignment of nucleotide sequences in an appropriate length indicated that the genotypes of these isolates were 4 and not 1c. For a more detailed analysis, the nucleotide sequences of the HCV E1 region as well as the core region for the same Yemeni patient were determined. A phylogenetic tree of the E1 region confirmed that the genotype of the HCV isolate from the Yemeni patient was 4. These data indicate that even when classifying HCV isolates using phylogenetic analysis, the misclassification would occur if care is not taken regarding the number and sequence lengths of the isolates included in the analysis.     

Genetics of fruit body production in higher basidiomycetes II. Monokaryotic and dikaryotic fruiting in schizophyllum commune

Summary In the wood destroying fungus Schizophyllum commune, a well known subject for genetic studies, fruit bodies are produced not only in the course of the sexual cycle but also asexually. Sexual fruiting requires the establishment of a dikaryon which is under the control of the incompatibility factors A and B. Asexual fruiting, however, starts directly from a monokaryon. The initiation of monokaryotic fruiting requires the presence of a single gene leading to the differentiation of fruit body initials. The action of at least two more genes is required for the further morphogenetic steps resulting eventually in the production of fruit bodies which differ in shape from dikaryotic fruit bodies. As a consequence of a mitosis their basidia produce two spores only. The three genes responsible for monokaryotic fruiting are pleiotropic and determine synergistically the timing of dikaryotic fruiting within a range between 6 to 20 d or longer. A fourth gene was found which codes epistatically for the formation of dome-like masses of stromatic tissue, thus directing morphogenesis into a side track.     

Central nervous system inflammatory response after cerebral infarction as detected by magnetic resonance imaging

Brain inflammation contributes to the tissue injury caused by ischemic stroke. Macrophages as the most abundant inflammatory cell population in stroke lesions can be visualized using ultrasmall superparamagnetic iron oxide (USPIO) as a cell-specific contrast agent for magnetic resonance imaging (MRI). The aim of our present study was to delineate the inflammatory response during experimental cerebral infarction by means of USPIO-enhanced MRI and to correlate the spatial distribution of USPIO-induced MR signal alterations with cellular infiltration and iron deposition. To this end USPIOs were administered to Wistar rats 5 days after photothrombotic cerebral infarction. MR imaging at 7 T performed 24 h later displayed a rim-like signal loss around the infarction in the USPIO treated animals. On histological brain sections obtained from the same animals after MRI the distribution of iron and ED1+ phagocytes was in full spatial agreement with the signal loss seen on T2*-weighted images. Our study validates USPIO-enhanced MRI as an important tool for the noninvasive visualization of brain inflammation in stroke and other CNS pathologies.     

Variation in serum electrolytes and enzyme concentrations in patients with sickle cell disease.

AIM--To assess levels of some biochemical variables in sickle cell disease patients from eastern Saudi Arabia during steady state and in crises states, with a view to comparing biochemical and clinical manifestations of the disease with those in other geographical locations. METHODS--Serum calcium, uric acid, total bilirubin, lactate dehydrogenase, hydroxybutyrate dehydrogenase, and haemoglobin were measured in 110 sickle cell patients when in steady state. The same variables were measured on 30 of the patients when they went into crisis. RESULTS--Serum calcium tended to be lower in sickle cell patients than in healthy controls, while uric acid tended to be in the high normal range. Crises did not make any difference to serum calcium but they increased the uric acid level significantly. All the other variables measured were significantly abnormal and more so during crises. CONCLUSIONS--Although the abnormal levels obtained for these biochemical variables in patients with sickle cell disease from eastern Saudi Arabia were similar to those from other geographical locations, there were noticeable differences in the severity of the abnormalities, which probably explains the differences in the clinical manifestations of the disease between geographical locations. Values of some of these variables could be adapted for use to monitor crises.     

Autonomous histopathological regression of primary tumours associated with specific immune responses to cancer antigens

Spontaneous histopathological regression of cancer has been reported. The involvement of the immune system in such regression has been advocated, leading to the theory of immunological surveillance against cancer. A prediction of this theory is that common tumour antigens can be recognized upon repeated exposure by cell-mediated immunity, which leads to tumour regression and the subsequent appearance of tumour antigen-loss variants. However, no direct evidence has been provided in non-viral-induced experimental animal models of primary malignancy or in human primary cancer. This study examined two groups of melanoma patients where histopathological regression of the primary tumour was observed. Many of the 23 patients with multiple (> or =3) primary melanomas showed significant regression of their last melanoma (median 33%, mean 40) compared with matched melanomas from patients with a single primary melanoma (median 0%, mean 12) (p=0.0080), or compared with their first primary melanoma (p=0.0013). Regression was consistent with an 'immunization effect' seen in murine tumour transplantation studies, where inoculation with > or =3 asynchronous tumours induces transplantation rejection on subsequent challenge. A significant decrease in the expression of the melanoma common tumour antigen MART-1 in the last primary tumour from multiple melanoma patients (median 8%, mean 24) versus matched single melanoma patients (median 79%, mean 68) (p=0.0041) and in the last versus first tumour in multiple primary patients was found (p=0.0083). Metastases from 17 patients whose primary skin melanomas had completely regressed (occult primary melanoma) also showed significant MART-1 loss (median 0%, mean 11) compared with matched metastases from patients with non-regressing primary melanoma (median 51%, mean 50) (p=0.0013). MART-1 antigen-loss variants observed in the multiple primary and occult primary patients correlated with the presence of peripheral blood MART-1-specific cytotoxic T lymphocytes (CTLs) (p=0.03). No similar effects were observed with two other melanoma antigens, gp100 and CD63. Thus, in two groups of human melanoma patients, evidence is provided for histopathological tumour regression associated with cancer immune surveillance.