An analytical model (Datta and Kotamarthi, 1990) for the electrokinetic dispersion coefficient in capillary electrophoresis (CE), for the case of low zeta-potential, that accounts for the effects of pressure-driven and/or electroosmotic flow of the elutant, is utilized here to theoretically explore the performance of CE in terms of plate height, plate number, peak resolution, resolving power, and the time of analysis. Practical operating conditions for the voltage gradient and Poiseuille flow fraction, v, are explored that optimize CE column performance. The implications of the results in the rational design of CE columns are discussed. It is also shown that the superposition of Poiseuille flow on the natural electroosmotic flow, while allowing greater freedom in the choice of elutant velocity, does not always cause increased dispersion.

Capillary Action↗

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Cancer of the buccal mucosa: are margins and T-stage accurate predictors of local control?

UNLABELLED: Cancer of the buccal mucosa is an uncommon and aggressive neoplasm of the oral cavity. Less than 2% of patients treated for cancer of the oral cavity at Roswell Park Cancer Institute (RPCI) from 1971 to 1997 had primary buccal cancers. Because the majority of these patients did not undergo any adjuvant treatment, this group provided us with the opportunity to assess the relationship between margin status and local recurrence for both small (T1-T2) and large (T3-T4) tumors treated with surgery alone. MATERIALS AND METHODS: The RPCI tumor registry database reported 104 patients who were treated for buccal carcinoma. A retrospective chart review identified 27 patients who met our criteria for a buccal mucosal primary tumor (epicenter of the mass in the buccal mucosa). There were 13 men and 14 women, ranging in age from 34 to 94 years (mean, 75). Data were collected regarding patient demographics, presenting symptoms, stage, treatment received, and outcome. RESULTS: All patients underwent surgical resection of their primary lesion; 21 (75%) had T1 or T2 tumors. The rate of local recurrence was 56% for the group as a whole. Patients with close or positive margins had a 66% local failure rate as compared with 52% when surgical margins were negative (greater than or equal to 5 mm from the resection margin after tissue fixation; P = ns). Among those in whom negative margins were achieved, patients with T1-T2 disease had a 40% local failure rate with surgical resection alone. CONCLUSIONS: Local excision of T1 and T2 buccal mucosa cancers with pathologically negative margins had a high rate of local recurrence in our series. Low T-stage and negative margins are not adequate predictors of local control. Even early buccal tumors may benefit from adjuvant therapy to enhance local control.

Adult↗

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Aetiology and outcome of acute viral hepatitis in pregnancy.

The aetiologic types of sporadic acute viral hepatitis in 169 pregnant women were compared with those of 70 non-pregnant women and 287 adult men. The majority of pregnant women (87.6%) came with acute hepatitis in the last trimester of pregnancy. Non-A, non-B (NANB) hepatitis accounted for 81.6% of hepatitis during pregnancy in comparison with 48.6% in non-pregnant women and 57.1% in adult men. Hepatitis A was extremely uncommon during pregnancy. Hepatitis B infection accounted for 17% of all cases in pregnant women compared with 45% in controls. Acute viral hepatitis in pregnancy had a poor outcome as assessed by maternal and/or fetal mortality (28.5%). The outcome was equally bad in hepatitis NANB and hepatitis B. Pregnant women generally had significantly lower immunoglobulin levels in comparison with non-pregnant women. In acute NANB hepatitis during pregnancy, serum IgG and IgM levels were lower and higher, respectively, compared with those in non-pregnant women and pregnant women with acute hepatitis B. It is suggested that an immune suppression during pregnancy might be responsible for increased susceptibility to acute NANB viral hepatitis, which, by itself, seems to induce only a transient acute phase IgM response.

Female↗

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Electron beam depth dose scaling by means of effective atomic number reconstructed from CT scans.

A method is developed by which the computed tomography scans of a medium carried out at a number of diagnostic energies can be utilized to obtain the in situ "Effective Atomic Number" and "Effective Density". The electron depth dose curves in water when scaled by these factors estimate the actual electron depth dose distribution in that medium. It appears that the use of CT scans for electron beam treatment planning, in the management of cancer, is quite promising.

Electrons↗

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Quantitative determination of tolerance doses for preoperative and postoperative radiotherapy of bones.

A method has been developed for the quantitative determination of the tolerance doses for preoperative and postoperative radiotherapy of bones in New Zealand white rabbits. The midshaft osteotomy was carried out on both ulnae of each rabbit. Localized radiation of 2000, 3000, and 4000 rad (20, 30, and 40 Gy) was given in daily fractions of 500 rad to different groups of rabbits. The diaphyseal area of one forearm of each rabbit was irradiated and the other forearm was used as a control. After healing, the mechanical strength of each ulna was measured. The end point is defined as "strength reduction dose-63" (SRD63), i.e., the dose which would be expected to reduce the mechanical strength of the irradiated, fractured, and healed bone compared with the contralateral unirradiated diaphysis by 63%. The SRD63's for preoperative and postoperative radiotherapy were 4350 rad (43.5 Gy) and 6200 rad (62 Gy), respectively, with a 500 rad (5 Gy)/fraction schedule. Through the use of the nominal standard dose (NSD) formula at 300 rad (3 Gy)/fraction and five fraction per week, these SRD63's are equivalent to 5700 rad (57 Gy) and 8100 rad (81 Gy), respectively.

Animals↗

PubMedDate not supplied

Etiologic spectrum of acute sporadic viral hepatitis in children in India.

The relative magnitude by hepatitis A virus (HAV), hepatitis B virus (HBV) and hepatitis Non-A, Non-B virus (HNANBV) was determined in 496 children from three different parts of India suffering from acute viral hepatitis by tests for specific IgM class anti-HAV and anti-HBV antibodies in the serum. HAV, HBV and NANB infections accounted for 55.8 per cent, 20.2 per cent and 23.2 per cent of cases respectively. Hepatitis A largely (59.5%) affected younger children of 1-5 yr. Nearly a third of children affected by NANB hepatitis were additionally positive for HBsAg. The proportions of HAV and HBV infected cases respectively decreased and increased with increasing age whereas the incidence of HNANBV infection remained almost constant throughout childhood. Acute NANB hepatitis, a major health problem in the adults of India is also common throughout childhood. This study suggests that this infection does not impart long lasting protective immunity.

Adolescent↗