Steady-state levels of uroporphyrinogen decarboxylase mRNA in lymphoblastoid cell lines from patients with familial porphyria cutanea tarda and their relatives

Familial porphyria cutanea tarda (PCT) results from a generalized deficiency of uroporphyrinogen decarboxylase (URO-D) activity. The molecular defect responsible for this disorder has not been characterized. To determine whether decreased levels of URO-D mRNA are responsible for subnormal URO-D activity, steady-state levels of URO-D mRNA in lymphoblastoid cells were determined. Northern blots were hybridized with a URO-D cDNA probe and quantified by densitometry. No difference in the levels of URO-D mRNA was detected between affected individuals and their normal relatives. Thus, the deficiency of URO-D activity in two familial PCT pedigrees characterized here does not arise from a deficiency of URO-D mRNA.

Familial porphyria cutanea tarda: hybridization analysis of the uroporphyrinogen decarboxylase locus

Familial porphyria cutanea tarda (PCT) results from a deficiency of uroporphyrinogen decarboxylase (URO-D) activity. Hybridization analysis of genomic DNA from unrelated normal individuals and PCT pedigree members failed to detect any major deletions, rearrangements or restriction fragment length polymorphisms at the URO-D locus.

Measurements of dose distributions in small beams of 6 MV x-rays

Dose distributions produced by small circular beams of 6 MV x-rays have been measured using ionisation chambers of small active volume. Specific quantities measured include tissue maximum ratios (TMR), total scatter correction factors (St), collimator scatter correction factors (Sc) and off-axis ratios (OAR). Field sizes ranged from 12.5 to 30 mm diameter, and were defined by machined auxiliary collimators with the movable jaws set for a 4 cm x 4 cm field size. Due to the lack of complete lateral electronic equilibrium for these small fields, the accuracy of the measurements was also investigated. This was accomplished by studying dose response as a function of detector size. Uncertainties of 2.5% were observed for the central axis dose in the 12.5 mm field when measuring with an ionisation chamber with a diameter of 3.5 mm. The total scatter correction factor exhibits a strong field size dependence for fields below 20 mm diameter, while the collimator scatter correction factor is constant and is defined by the setting of the movable jaws. Off-axis ratio measurements show larger dose gradients at the beam edges than those achieved with conventional collimator systems. Corrected profiles measured with an ionisation chamber are compared with measurements made with photographic film and LiF thermoluminescent dosemeters.

A new system for patient fixation in radiotherapy

A new system for patient fixation in radiation treatment is described. The system consists of an airtight plastic bag with a contents of polysterol microspheres. A valve allows evacuation which results in a rigid close fitting cast. The system was compared with conventional foam cast fixation in 29 patients who were treated for carcinoma of the breast. The patients received radiation treatment over 22 fractions, and portal X-ray pictures were obtained at every second treatment. The portal films were compared with the stimulator radiographs and the variation in the position of the centre cross were measured in cranio-caudal and transversal direction as well as the rotation of the centre cross. The results showed that the daily reproducibility of the patient set-up was considerably improved by the new system, the centre cross deviation of the position of the actual radiation field to the centre cross of the intended field being less than 1 mm in 50% of the cases. The system is time-saving and cheap compared to conventional fixation systems.

Isolation of a gene segment expressed by mature schizonts of Plasmodium knowlesi

Fragments of Plasmodium knowlesi DNA, generated by mung bean nuclease digestion, were ligated into the lambda gt11 vector. This expression library was immunoscreened with a serum which inhibits invasion of erythrocytes by merozoites in vitro and whose primary specificity is directed against a Mr 140 000 merozoite surface antigen. One of the isolated clones contained a 125 base pair insert which hybridized to a 1.8 kilobase species of schizont RNA, indicating that this insert is part of a gene expressed during schizogony.

A scanning-slit x-ray videoabsorptiometric technique for bone mineral measurement

An x-ray videoabsorptiometric technique was developed for measurement of bone mineral content (BMC) in vivo. The principle utility of this technique is the precise measurement of commonly fractured bones, such as the femoral neck, that are difficult to measure by other techniques because of repositioning problems. Scanning slits reduce scattered radiation and improve linearity of measurements. Heavily filtered, high-kVp beams are used to minimize errors from beam hardening, and data renormalization is employed to compensate for spatial nonuniformities of the beam and detector. Linearity of measured BMC over the range 0.8 to 5 g/cm2 is very good (r = 0.998) and compares well to single- and dual-photon absorptiometry. A 1.6% change in measured BMC is observed for a 10% change (approximately 2 cm) in tissue thickness while a 10% change in marrow type causes a 0.6%-0.8% change in BMC. Manual repositioning of a femur phantom revealed a variation of 0.84% over ten measurements when femur values were referenced to standards. A computer repositioning algorithm provides much easier identification of the region for analysis and yields comparable variation (0.9%).

Mung bean nuclease cleaves Plasmodium genomic DNA at sites before and after genes

Mung bean nuclease was found to cut the genomic DNA of the malaria parasite Plasmodium at positions before and after genes but not within gene-coding regions. This cleavage, which had nearly the preciseness of a restriction nuclease, required controlled conditions in the presence of formamide. Southern blot analysis showed that the coding areas for Plasmodium actin, circumsporozoite protein, histidine-rich protein, ribosomal RNA's, and tubulin are each cleaved from genomic DNA to yield a single major band on an agarose gel. DNA sequence data on several clones of mung bean nuclease cleavage products containing the gene for the circumsporozoite protein of Plasmodium falciparum confirmed that cleavage sites are before and after genes. Recognition and cleavage of DNA did not seem to be related to any primary sequence but may be related to structural features of the DNA duplex that demarcate genes. Mung bean nuclease-cleaved DNA could be inserted directly into a lambda expression vector, yielding a representative but small gene bank of intact gene fragments.

Development of a Danish preventive program for preschoolchildren based on cooperation with key-persons

Plans to expand public child dental services to include preschoolchildren and the recently established training of dental hygienists in Denmark form the background for the present study. The study was performed in a rural municipality located 35 km north of Aarhus. Public child dental services for schoolchildren (6-16 years of age) had been established for several years and were being planned to include preschoolchildren. In cooperation with the personnel in the Child Dental Service a full-time employed dental hygienist developed a communication network with different categories of key-persons (health nurses, private daycare mothers and nursery school teachers). Close records and diaries were kept during the entire 3-year study period. The paper summarises the experience gained from co-operation with a large number of key-persons and illustrates some of the conditions necessary for a successful process. The effect of the program on dental caries is discussed.

Drug interference with laboratory value interpretation: A review

In patients receiving medication, laboratory determinations can be adversely affected by drug-induced physiologic side effects and/or direct analytic interference by the drug or its metabolites. Drugs administered to alleviate an illness can induce physiologic abnormalities in one or more of the following systems: hepatic, hemostatic, renal, hematologic, pancreatic, muscular and osteal, with the result that correct diagnosis is obscured or proper monitoring is prevented. Drug interference can also occur directly in analytic laboratory assays, producing falsely elevated or decreased values.

Quantitation of serum tobramycin concentration using high-pressure liquid chromatography

A high-pressure liquid chromatography method for the quantitative determination of tobramycin in serum is described. The antibiotic was separated from serum by chromatography on a silica gel column. The adsorbed antibiotic was derivatized with o-phthalaldehyde, and then eluted with isopropanol. The derivatized tobramycin was separated by reverse-phase chromatography and quantitated by fluorometry. Serum concentrations as low as 0.5 microgram/ml could be accurately measured. A linear response for serum samples containing tobramycin ranging from 0 to 20 microgram/ml was obtained. Other antibiotics, including various aminoglycosides, did not interfere with the tobramycin assay. Comparison with a standard microbiologic assay gave a correlation coefficient of 0.99. This chemical assay is sensitive, precise, specific, and can be performed in 30 minutes.

Direct assays of lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate with a centrifugal analyzer

Methods are described for direct assays of lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate in plasma with the GEMSAEC centrifugal analyzer. The methods for lactate, beta-hydroxybutyrate, and acetoacetate are kinetic and ratiometric, eliminating the need for specimen-blank assays. The pyruvate method is an end-point assay, because endogenous lactate dehydrogenase interferes in a kinetic pyruvate assay. The methods are precise and accurate and 1-min of analysis time is adequate for each assay. Rapid assessment and monitoring of metabolic acidosis is possible with these methods, as is illustrated by examples.

Direct assays of lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate with a centrifugal analyzer

Methods are described for direct assays of lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate in plasma with the GEMSAEC centrifugal analyzer. The methods for lactate, beta-hydroxybutyrate, and acetoacetate are kinetic and ratiometric, eliminating the need for specimen-blank assays. The pyruvate method is an end-point assay, because endogenous lactate dehydrogenase interferes in a kinetic pyruvate assay. The methods are precise and accurate and 1-min of analysis time is adequate for each assay. Rapid assessment and monitoring of metabolic acidosis is possible with these methods, as is illustrated by examples.

Serum gentamicin assay by high-performance liquid chromatography

We describe a high-performance liquid chromatographic method for the quantitative determination of gentamicin in serum. The antibiotic was separated from serum by passage through a silicic acid column, derivatized with o-phthalaldehyde, and eluted with ethanol. The derivatized gentamicin was then separated into all three of its major components by reversed-phase chromatography and quantified by fluorometry. Concentrations in serum as low as 0.5 mg of gentamicin per liter could be accurately determined. A standard curve showed a linear response for serum containing gentamicin at concentrations ranging from 0 to 20 mg/liter. Tobramycin, amikacin, ampicillin, penicillin G, methicillin, carbenicillin, chloramphenicol, clindamycin, and cephalothin did not interfere with the gentamicin assay. Comparison with an accepted microbiological assay yielded a correlation coefficient of 0.99. This chemical assay is rapid (less than 30 min), sensitive, accurate, specific, and appears to be applicable to other aminoglycosides.

Serum gentamicin assay by high-performance liquid chromatography

We describe a high-performance liquid chromatographic method for the quantitative determination of gentamicin in serum. The antibiotic was separated from serum by passage through a silicic acid column, derivatized with o-phthalaldehyde, and eluted with ethanol. The derivatized gentamicin was then separated into all three of its major components by reversed-phase chromatography and quantified by fluorometry. Concentrations in serum as low as 0.5 mg of gentamicin per liter could be accurately determined. A standard curve showed a linear response for serum containing gentamicin at concentrations ranging from 0 to 20 mg/liter. Tobramycin, amikacin, ampicillin, penicillin G, methicillin, carbenicillin, chloramphenicol, clindamycin, and cephalothin did not interfere with the gentamicin assay. Comparison with an accepted microbiological assay yielded a correlation coefficient of 0.99. This chemical assay is rapid (less than 30 min), sensitive, accurate, specific, and appears to be applicable to other aminoglycosides.

Refractory pneumothorax treated by parietal pleurolysis

Pneumothorax, persisting in spite of efficient drainage, may in some cases be caused by discrepancy between lung volume and size of the pleural cavity. The logical treatment is reduction of the pleural cavity simultaneously with a traditional surgical procedure on the pulmonary tissue. An increasing number of refractory pneumothoraces--both spontaneous and istrogenic--is probably due to the fact that more people are living with and suffer the sequelae of pulmonary disease. During a 15-year survey a parietal pleurolysis, tailored to fit the size and shape of the lung, was performed in 10 patients as the main surgical procedure in 100 thoracotomies for 1130 cases of spontaneous and 62 cases of iatrogenic pneumothorax. The results were encouraging.

Surgical treatment of "tuberculoma". A follow-up examination of patients with pulmonary tuberculosis resected on suspicion of tumour

On suspicion of tumour, thoracotomy was performed in 91 patients, who proved to have pulmonary tuberculosis. Short-term antituberculous chemotherapy was given pre-operatively in 66 cases. The 89 surviving patients received antituberculous chemotherapy after operation, and were examined one year after its termination. No signs of dissemination or other tuberculous manifestations were found, whether pre-operative therapy had been given or not.

A comparison of the Murphy-Pattee and the Seligson methods for serum thyroxine

We compared two methods for serum thyroxine measurement by competitive protein binding - the Murphy and Pattee and the Seligson and Seligson methods. We found the Seligson and Seligson method, which requires less sample volume and analysis time, to be the method of choice on the basis of sensitivity, extraction efficiency, precision, and accuracy. Standard plots of time/10,000 counts versus thyroxine concentration are linear to 20 ug/dl, extraction efficiency is 99.6 per cent, within-day S.D. plus or minus 0.28 ug/dl, and 98.3 per cent of added thyroxine is recovered in the Seligson and Seligson method. The Seligson and Seligson method is superior to the Murphy and Pattee method with respect to all these parameters. The methods were also compared with correlation and normal value studies.