Dental management of patients irradiated for oral cancer

Management of patients irradiated for oral cancer should include consideration of their oral health prior to, and after, radiation therapy. Data from 130 patients, followed for a period of 1 to 10 years, are presented and evaluated. The philosophy of retention and maintenance of as many teeth as possible is supported by this data. Extraction of teeth with severe periodontal disease after irradiation also proves to be a relatively safe operation. Osteoradionecrosis tends to be limited in extent and is generally well tolerated by the patient when treated conservatively. A treatment regimen is presented that significantly reduces the morbidity from therapeutic irradiation of the jaws. A comprehensive dental evaluation and follow-up plan coupled with patient cooperation are instrumental to the success of this program.     

Differing effects of the vasodilator drugs, prazosin and diazoxide on plasma renin activity in the dog

1. The effects of intravenous (i.v.) administration of the vasodilator drugs prazosin or diazoxide on blood pressure and plasma renin activity were evaluated in the anaesthetized dog. 2. Prazosin and diazoxide both induced a rapid reduction in the mean arterial pressure to 73% and 75% of control values respectively. 3. Prazosin lowered plasma renin activity to 62% (P less than 0-025) of the control value whereas diazoxide raised plasma renin activity to 178% (P less than 0.05) of the control value. 4. The combination of vasodilatation and low renin activity observed following the administration of prazosin is unique, and may have clinical significance if these factors reduce the vascular complications of hypertension.     

Author index to volume 52

Domains of complicated boundary shape are of great practical importance in several fields of technology and applied science; e.g. solid propellant rocket grains, electromagnetic and acoustic waveguides, and certain elements used in nuclear engineering. The technical literature contains very few comparative studies of analytical and numerical solutions when dealing with such rather complex geometries. The present study constitutes an effort in that direction.     

Hemodynamic effects of vasodilator agents in dogs with experimental ventricular septal defects

The ratio of pulmonary to systemic vascular resistance (Rp/Rs) largely determines the amount of left-to-right shunting and pulmonary to systemic flow rat (Qp/Qs) in the presence of a large isolated ventricular septal defect. The possibility that pharmacologic reduction of systemic vascular resistance with alpha-adrenergic receptor blockade or beta-adrenergic receptor stimulation would increase the ratio Rp/Rs, and therefore reduce the ratio Qp/Qs, was studied in dogs in which ventricular septal defects had been surgically created. Administration of phentolamine and phenoxybenzamine caused a 42% reduction in Rs and no reduction in Rp. Qs was unchanged and Qp declined by 24% and the ratio Qp/Qs fell by 32%. Infusion of the beta-adrenergic receptor stimulant isoproterenol also reduced Qp/Qs. However, this was accomplished as a result of an increase in Qs and at the expense of an increase in heart rate. As a decline in the ratio Qp/Qs has been shown to be beneficial to patients with large left-to-right shunts, pharmacologic reduction of systemic vascular resistance may prove to be helpful in treating congestive heart failure in those patients with large left-to-right shunts at the ventricular level who are refractory to the usual decongestive measures.     

Mortality and some biochemical changes in mink (Mustela vison) given sublethal doses of aflatoxin each day

Two feeding trials were done to study the susceptibility of mink (Mustela vison) to multiple sublethal doses of aflatoxins. In the 1st trial, twenty 3-month-old male mink were divided equally among groups. Each mink in groups 1, 2, 3, and 4 was given a meatball daily that contained 15, 30, 45, or 0 mug of aflatoxins (B1:G1, 40:60), respectively. All mink in group 3 died between the 25th and the 30th days of the feeding trial. Each mink had ingested 1,035 to 1,480 mug of aflatoxins. Four of the mink in group 2 died almost as soon as did mink in group 3. Four mink in group 1 died between 40 and 59 days after the start of the feeding trial. Generally, a marked increase in plasma cholesterol and alkaline phosphatase activity appeared before mink died. The liver from animals that died of aflatoxicosis showed prominent pathologic changes which included hemorrhages and appearance of pink yellow spots. Histopathologic examination of liver from dead mink revealed fatty infiltration, bile duct proliferation, bile stasis, pseudotubular formation, congestion, and fibrosis. The feeding trial was repeated with 20 mink (8 males and 12 females) that were 1.5 to 2 years old. In this instance, 0, 20, 40, and 60 mug of aflatoxins were administered each day. All treated animals, except 1, were dead within 37 days after the experiment started. The survivor was given the lowest dosage of toxins and died after 52 days by which time 960 mug of aflatoxins were consumed. Plasma cholesterol content and alkaline phosphatase activity generally were similar to those observed in younger mink of the 1st feeding trial.     

Spectroscopic studies and evanescent optical fibre wave sensing of Cu<Superscript>2+</Superscript> based on activated mesostructured silica matrix

This paper report on the synthesis and test of eriochrome cyanine R (ECR) doped mesostructured silica films as Cu²⁺ sensing without prior removal of the surfactant. ECR activated mesostructured silica (via sol-gel technique) coated optical fibre core were used to Cu²⁺ sensing by evanescent wave method. The sol was prepared via acidic hydrolysis-condensation of tetraethoxysilane (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB:C₁₆H₃₃NCH₃Br) as the structure-directing agent. Spectrophotometric investigations using doped sol-gel thin films dip-coated on glass slides were reported. Heat treatment temperature effect (optimum temperature 150°C), absorption dependence on the pH of the aqueous phase (pH = 8 seems to be the optimal absorption pH), sensitivity, reversibility and response range (0.05 mmol/l) were reported.     

An inverse method for radiation transport

Adjoint functions have been used with forward functions to compute gradients in implicit (iterative) solution methods for inverse problems in optical tomography, geoscience, thermal science and other fields, but only once has this approach been used for inverse solutions to the Boltzmann transport equation. In this paper, this approach is used to develop an inverse method that requires only angle-independent flux measurements, rather than angle-dependent measurements as was done previously. The method is applied to a simplified form of the transport equation that does not include scattering. The resulting procedure uses measured values of gamma-ray fluxes of discrete, characteristic energies to determine interface locations in a multilayer shield. The method was implemented with a Newton-Raphson optimisation algorithm and it worked very well in numerical 1-D spherical test cases. A more sophisticated optimisation method would better exploit the potential of the inverse method.     

Typing of multiple single-nucleotide polymorphisms using ribonuclease cleavage of DNA/RNA chimeric single-base extension primers and detection by MALDI-TOF mass spectrometry

A novel single-base extension (SBE) assay using cleavable and noncleavable SBE primers in the same reaction mix is described. The cleavable SBE primers consisted of deoxyribonucleotides and one ribonucleotide (hereafter denoted chimeric primers), whereas the noncleavable SBE primers consisted of only deoxyribonucleotides (hereafter denoted standard primers). Biotin-labeled ddNTPs were used in the SBE reaction, and the SBE products were purified using the monomeric avidin triethylamine purification protocol, ensuring that only primers extended with a biotin-ddNTP in the 3'-end were isolated. A ribonuclease mix was developed to specifically cleave the chimeric primers, irrespective of the base of the ribonucleotide, whereas standard primers without a ribonucleotide were unaffected by the ribonuclease treatment. The SBE products were analyzed in linear mode using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. The cleaved SBE products were detected in the 2000-5500 m/z range, and the noncleaved SBE products were detected in the 5500-10 000 m/z range. The method was validated by typing 17 Y chromosome single-nucleotide polymorphisms in 100 males with a 17-plex SBE package containing 9 chimeric primers and 8 standard primers.