Stabilization of an inserted tricalcium phosphate spacer enhances the healing of a segmental tibial defect in sheep

The effect of inserting a tricalcium phosphate (TCP) spacer stabilized by a rigid or non-rigid fixation technique on the healing of segmental tibial defects of critical size was established. The osteotomized tibiae, 11 with and 8 without TCP spacers, were fixed by an external circular device in 11 mature sheep and by plates in 8 mature sheep, respectively. Healing was evaluated roentgenographically 16 weeks after the operation. Compared with the defects without TCP spacers, enhanced stability and healing were observed in the defects with TCP spacers under an identical external fixation. Furthermore, a significantly higher incidence of healing was obtained with plate fixation than with external device fixation in the TCP-implanted defects (P < 0.04). An abundant bridging callus was roentgenograpically demonstrated in most of the healed defects, but none in the unhealed defects. The TCP spacer with its mechanical integrity enhances the stability of external fixation, and the stable immobilization provided by rigid fixation is essential for osteoconduction of an inserted TCP spacer in the healing of segmental diaphyseal defects in sheep.     

Conserved features in papillomavirus and polyomavirus capsids

Capsids of papilloma and polyoma viruses (papovavirus family) are composed of 72 pentameric capsomeres arranged on a skewed icosahedral lattice (triangulation number of seven, T = 7). Cottontail rabbit papillomavirus (CRPV) was reported previously to be a T = 7laevo (left-handed) structure, whereas human wart virus, simian virus 40, and murine polyomavirus were shown to be T = 7dextro (right-handed). The CRPV structure determined by cryoelectron microscopy and image reconstruction was similar to previously determined structures of bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 1 (HPV-1). CRPV capsids were observed in closed (compact) and open (swollen) forms. Both forms have star-shaped capsomeres, as do BPV-1 and HPV-1, but the open CRPV capsids are approximately 2 nm larger in radius. The lattice hands of all papillomaviruses examined in this study were found to be T = 7dextro. In the region of maximum contact, papillomavirus capsomeres interact in a manner similar to that found in polyomaviruses. Although papilloma and polyoma viruses have differences in capsid size (approximately 60 versus approximately 50 nm), capsomere morphology (11 to 12 nm star-shaped versus 8 nm barrel-shaped), and intercapsomere interactions (slightly different contacts between capsomeres), papovavirus capsids have a conserved, 72-pentamer, T = 7dextro structure. These features are conserved despite significant differences in amino acid sequences of the major capsid proteins. The conserved features may be a consequence of stable contacts that occur within capsomeres and flexible links that form among capsomeres.     

cDNA cloning of a human homologue of the Caenorhabditis elegans cell fate-determining gene mab-21: expression, chromosomal localization and analysis of a highly polymorphic (CAG)n trinucleotide repeat

The two most consistent features of the diseases caused by trinucleotide repeat expansion-neuropsychiatric symptoms and the phenomenon of genetic anticipation-may be present in forms of dementia, hereditary ataxia, Parkinsonism, bipolar affective disorder, schizophrenia and autism. To identify candidate genes for these disorders, we have screened human brain cDNA libraries for the presence of gene fragments containing polymorphic trinucleotide repeats. Here we report the cDNA cloning of CAGR1, originally detected in a retinal cDNA library. The 2743 bp cDNA contains a 1077 bp open reading frame encoding 359 amino acids. This amino acid sequence is homologous (56% amino acid identify and 81% amino acid conservation) to the Caenorhabditis elegans cell fate-determining protein mab-21. CAGR1 is expressed in several human tissues, most prominently in the cerebellum, as a message of approximately 3.0 kb. The gene was mapped to 13q13, just telomeric to D13S220. A 5'-untranslated CAG trinucleotide repeat is highly polymorphic, with repeat length ranging from six to 31 triplets and a heterozygosity of 87-88% in 684 chromosomes from several human populations. One allele from an individual with an atypical movement disorder and bipolar affective disorder type II contains 46 triplets, 15 triplets longer than any other allele detected. Though insufficient data are available to link the long repeat to this clinical phenotype, an expansion mutation of the CAGR1 repeat can be considered a candidate for the etiology of disorders with anticipation or developmental abnormalities, and particularly any such disorders linked to chromosome 13.     

A cytidine triphosphate synthetase gene in Plasmodium falciparum

The malarial parasite Plasmodium falciparum is dependent on de novo synthesis for its pyrimidine nucleotide requirements. However, the activity of the key enzyme in cytidine nucleotide synthesis, CTP synthetase (EC 6.3.4.2), has not been reported. We present evidence for a CTP synthetase gene in P. falciparum, having isolated a PCR product obtained using 2 primers derived from the CTP synthetase amino acid consensus sequences DPYINVDPG and GICLGMQ. The amplified DNA segment encodes an amino acid sequence with considerable homology to CTP synthetases from several other species including human and yeast.     

Jugular bulb oximetry for the monitoring of cerebral blood flow and metabolism

Jugular bulb oximetry can be used to assess the balance between oxygen supply and demand to the brain, measure metabolic byproducts, and determine cerebral blood flow. It has been useful in guiding the management of patients who are at risk of developing global ischemia. In this article, the principles upon which this monitor is based are discussed. Technical considerations such as placement techniques, factors affecting accuracy, limitations of the technique, and proper interpretation of oximetric values are reviewed. Lastly, specific clinical applications are presented.     

Correlates of membrane metabolism and long-term potentiation in slices of rat cerebral cortex

A group of interrelated parameters of the membrane metabolism was studied during stimulation of the lateral olfactory tract in the rat brain slices of olfactory cortex. All the parameters were studied in respect to electrical activity of the slices in three temporal points after the tetanisation: 3-5, 15, and 30 min. Regular phasic alterations of the metabolism parameters occurred in most of the cases. Their functional significance is discussed.     

Mortality mapping in Hong Kong, 1979-83 and 1984-88: the patterns of major non-malignant diseases

In this study, human platelets were used as a cellular model for exploring cytosolic free Ca (Cai) regulation in non-insulin-dependent diabetes mellitus (NIDDM). Cai levels were monitored in resting and thrombin-stimulated platelets from obese females with NIDDM; obese, nondiabetic women, and nonobese, nondiabetic women. All subjects were black. Significant and marked elevation of basal Cai levels was observed in platelets from the diabetic subjects when no aspirin was used during platelet isolation. However, no significant differences were observed in Cai between aspirin-treated platelets from women with NIDDM and platelets from nondiabetic women. The rate of the Cai return to basal level after thrombin stimulation was significantly lower in platelets from the diabetic subjects, suggesting an abnormality in platelet Ca extrusion or sequestration in NIDDM. Platelet Cai levels positively correlated with low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio (LDL/HDL) and fasting blood glucose. These findings suggest abnormalities in platelet Cai homeostasis in NIDDM that are influenced by the serum lipid profile and perhaps glucose.     

The preemptive effect of regional anesthesia on post-cesarean section pain

Chronologic age is an utmost important birth record in many industrialized Western countries. When the date of birth is unknown, there is a demand for establishing the chronologic age. Dental methods for age estimations are considered more reliable than most other methods by the majority of researchers and are among the most commonly used means to determine age. Traditionally, these methods have most often been based on subjectively estimated, radiographic stages of tooth development. In the present study metric measurements of the length of the forming root have been used and are compared with one standard method. The formed part of the root of the lower third molar as seen in a panoramic radiograph was digitized. Data were directly stored in a computer for subsequent statistical analysis. The technique of collecting data with the aid of a computer had some statistical advantages. The precision of age estimations was, however, slightly inferior to the standard method.