The maintenance of reproductive isolation in a mosaic hybrid zone between the fire-bellied toads Bombina bombina and B. variegata.

Mosaic hybrid zones arise when ecologically differentiated taxa hybridize across a network of habitat patches. Frequent interbreeding across a small-scale patchwork can erode species differences that might have been preserved in a clinal hybrid zone. In particular, the rapid breakdown of neutral divergence sets an upper limit to the time for which differences at marker loci can persist. We present here a case study of a mosaic hybrid zone between the fire-bellied toads Bombina bombina and B. variegata (Anura: Discoglossidae) near Apahida in Romania. In our 20 x 20 km study area, we detected no evidence of a clinal transition but found a strong association between aquatic habitat and mean allele frequencies at four molecular markers. In particular, pure populations of B. bombina in ponds appear to cause massive introgression into the surrounding B. variegata gene pool found in temporary aquatic sites. Nevertheless, the genetic structure of these hybrid populations was remarkably similar to those of a previously studied transect near Pescenica (Croatia), which had both clinal and mosaic features: estimates of heterozygote deficit and linkage disequilibrium in each country are similar. In Apahida, the observed strong linkage disequilibria should stem from an imperfect habitat preference that guides most (but not all) adults into the habitats to which they are adapted. In the absence of a clinal structure, the inferred migration rate between habitats implies that associations between selected loci and neutral markers should break down rapidly. Although plausible selection strengths can maintain differentiation at those loci adapting the toads to either permanent or temporary breeding sites, the divergence at neutral markers must be transient. The hybrid zone may be approaching a state in which the gene pools are homogenized at all but the selected loci, not dissimilar from an early stage of sympatric divergence.

RasG protein accumulation occurs just prior to amoebae emergence during spore germination in Dictyostelium discoideum.

RasG protein levels in dormant and germinating spores of Dictyostelium discoideum strains JC1 and SG1 were estimated by Western blotting. RasG levels were very low in dormant spores and remained low during the lag period, regardless of whether spores were heat activated or treated with autoactivator during the early stages of spore germination. RasG levels increased late during spore swelling just prior to the emergence stage of germination. These data are consistent with a requirement for RasG during vegetative growth.

Nasal bilevel positive airway pressure therapy in children with a sleep-related breathing disorder and attention-deficit hyperactivity disorder: effects on electrophysiological measures of brain function.

OBJECTIVE: To examine the effect of nasal bilevel positive airway pressure (BiPAP) treatment for concurrent sleep-related breathing disorders (SRBDs) and attention-deficit hyperactivity disorder (ADHD) on electrophysiological measures of spontaneous brain activity and auditory stimulus processing. METHODS: Nineteen children diagnosed with both SRBD and ADHD participated. Electroencephalogram (EEG) activity was recorded during a resting period and an auditory oddball task before beginning BiPAP treatment, after 6 months on treatment, and after a subsequent 1 week non-treatment period. Treatment effects on EEG and event-related potentials (ERPs) to target stimuli were examined via topographic analysis. RESULTS: Thirteen of the initial 19 children completed 6 months of BiPAP therapy, with six lost mainly due to compliance problems. Children on BiPAP therapy showed a significant decrease in slow-wave (delta and theta) and an increase in fast wave (beta) EEG activity. The P3 component of the ERP showed treatment effects in amplitude and latency. CONCLUSIONS: The electrophysiological data suggest that SRBDs may contribute to ADHD symptomatology. Treatment of SRBD with BiPAP therapy in children with concurrent ADHD can lead to significant changes, in the direction of normalization, of the typical electrophysiological features of ADHD.

Third ventriculostomy for shunt infections in children.

Four children with extracranial shunts for noncommunicating hydrocephalus suffered from recurrent or intractable shunt infections. All patients were resistant to or relapsed after treatment with intravenous and intrathecal antibiotics with change of the shunt apparatus. They were treated with neuroendoscopic third ventriculostomy and the removal of all implants, except for a reservoir in one patient. That child later had the reservoir removed because of persistent proteus infection. All patients received antibiotics for approximately 2 weeks after the operation. There was no morbidity associated with the procedure, and all patients remain shunt independent with follow-up periods of 21 to 46 months (mean, 33 mo), although one has needed another third ventriculostomy. We have shown that third ventriculostomy is a successful surgical intervention for the management of shunt infections in patients with noncommunicating hydrocephalus.

A32390A, a new biologically active metabolite. I. Discovery and fermentation studies.

A32390A is an isonitrile-containing derivative of diacyl D-mannitol. The compound is produced in fermentation as the major component of a metabolic complex known as A32390. A32390A inhibits dopamine-beta-hydroxylase reduces heart and adrenal norepinephrine levels, lowers blood pressure in hypertensive rats, and possesses antibiotic activity vs. Gram-positive bacteria and fungi, including Candida albicans. A32390 is produced in submerged culture by a mold, a species of Pyrenochaeta, NRRL-5786. Glucose and sucrose are among the best carbon sources for the biosynthesis of A32390. Mannitol, although a substituent of the A32390A molecule, supports little or no biosynthesis of the compound when employed as the major carbon source for the fermentation. The addition of crotonic acid derivatives. ethanol, or L-histidine to the fermentation medium enhances the level of A32390 produced.

Benign cementoblastoma: a case report.

The case of a 23-year-old with a benign cementoblastoma is presented. The clinicopathologic features, treatment and prognosis are discussed and a brief review of the literature is presented. Although this neoplasm is rare, the dental practitioner should be aware of the clinical features that will lead to its early diagnosis and treatment.

Drug use for the pregnant or lactating patient.

The dental patient who is pregnant or lactating may require management involving the administration or prescription of drugs. The approach of completely avoiding all drugs may not permit appropriate treatment of the patient and most often is not warranted. This article reviews the current considerations in the use of drugs in the dental patient who is either pregnant or lactating. The safety of the local anesthetics, vasoconstrictors, analgesics, antimicrobials, and sedatives used in dentistry is discussed.

Management considerations for the pregnant or nursing emergency patient.

It is important to realize the risk-benefit ratio in all therapeutic modalities in any patient and that these variables vary from patient to patient as do circumstances. The emergency patient who is pregnant or nursing should not be feared or be denied appropriate treatment. It is always best to err on the side of safety and remain conservative. The dental problem can usually be treated with the use of adequate local anaesthesia and supplemental nitrous oxide in the second or third trimester. Nevertheless, situations arise that may warrant consultation with the patient's physician or specialist. This brief overview should refamiliarize the dental practitioner with the medications available to treat the gravid patient. It is important to have an understanding of our common therapeutics as well as the inherent treatment risks and benefits as they relate to the changing maternal-fetal physiology.

Comparisons of genetic variability detected among mouse blood proteins using one- and two-dimensional electrophoreses.

Comparisons of the sensitivities of one-dimensional (1D) and two-dimensional (2D) electrophoreses to detect genetic variability have generally shown that the 2D approach appears to be two- to five-fold less sensitive than conventional 1D approaches. Concerns about the validity of this conclusion have arisen because such comparisons have involved mainly enzymic proteins in 1D approaches versus a complex mixture of soluble proteins in most 2D analyses. Comparisons involving the absolute number of variants detected, using 1D and 2D sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), denatured mouse blood proteins isolated from C3HeB/FeJ and C57B1/6J inbred strains of mice, and highly sensitive silver staining, indicate that the latter uncovers at least as much variability as the former. Although the relative percentage of variable bands (1D SDS-PAGE) was greater than the relative percentage of variable spots (2D SDS-PAGE) when proteins of intact erythrocytes were surveyed, both techniques uncovered approximately equal percentages of variable proteins when the mouse erythrocyte proteins were partitioned into membrane and lysate components. Therefore, the simpler 1D SDS-PAGE was found to be as effective as 2D SDS-PAGE in detecting protein variability. Since 1D SDS-PAGE separates proteins primarily on the basis of molecular weight and to a lesser degree on other primary protein sequence alterations, much of the variability observed by 2D SDS-PAGE may be due to these same features and unit charge differences may not play a significant role in detecting variability in the proteins studied. This differs from enzymic proteins, where such charge differences appear to be responsible for much of the variability. This study also indicated that decreasing the number of proteins in samples (membranes and lysates vs whole erythrocytes) increased the ability of both of these techniques to resolve differences. Mating studies indicated that most of the differences detected with both techniques were inherited and were not artifacts.

A computer program to assist in the choice of restriction endonucleases for use in DNA analyses.

Type II restriction endonucleases cleave double stranded DNA molecules at sites characterized by one or more sets of nucleotide pairs sequences. These digestions are essential in such procedures as DNA cloning, DNA sequencing and restriction fragment length polymorphism (RFLP) analyses. A large number of enzymes with different sequence specificities are available. To date, most choices of restriction endonucleases have been made by trial and error. A computer program, REDI, has been developed that predicts the ability of a particular restriction enzyme to detect mutations. Characteristics of both the restriction endonuclease used and the DNA being cut are incorporated as variables in the program. The program was tested using mouse mitochondrial DNA (mtDNA) and bacteriophage lambda DNA because these have been sequenced and are well characterized. REDI was strongly correlated (rs = +0.862, n = 11, P less than 0.001) with mouse mtDNA RFLP detected by Ferris et al. [1] (Genetics, 105 (1983) 681-721). Even though predictions may be altered by a non-random association of nucleotides, which varies among DNA molecules, the predictions increase the probability of selecting the most efficient enzymes for use in the analysis of a particular DNA molecule.

Odontogenic infections: Part one. Anatomy and radiology.

Odontogenic infections are frequently encountered by the dentist. The signs and symptoms of these common dental emergencies are outlined in this two-part article. A thorough knowledge of the fascial planes and anatomical routes of infection spread is a critical prerequisite to understanding the clinical manifestations, potential complications, and appropriate management of these infections.

Odontogenic infections: Part two. Microbiology, antibiotics and management.

This article deals with the microbiological aspects of infections, the principles and role of antibiotic use and the general management of the patient suffering from an odontogenic infection. Clinical aspects of the most common presentations will be addressed to understand the organized management of these challenging patients. (Part one appeared in Oral Health, May, 1995).

Fractures of the zygomatic complex: a case report and review.

Traumatic injuries to the midface are not nearly as common in Canada as they are in the United States, but practitioners must still be prepared for the evaluation and treatment of patients presenting with midface fractures. This case report demonstrates the experience one individual who presented with the clinical signs and symptoms of midfacial trauma. Cases of this nature can be confidently managed by an oral and maxillofacial surgeon. A review provides knowledge regarding anatomic features, classification schemes and the diagnostic and therapeutic decisions encountered with the treatment of zygomatic complex fractures. The forward projection of the zygoma causes it to be frequently injured secondarily to blunt trauma of the midface, at the expense of protecting the orbit.

Third molar surgery: current concepts and controversies. Part 1.

The removal of impacted third molar teeth ranks as the commonest procedure in the practise of oral and maxillofacial surgery. It is the purpose of this review article to present the major controversies and correct some of the misconceptions associated with third molar surgery. This paper deals primarily with the discussion of the indications for the removal while part II describes the influence of a variety of factors upon the outcome of third molar surgery.

Third molar surgery: current concepts and controversies. Part 2.

The outcome of third molar surgery is influenced by a variety of factors including among others, mucoperiosteal flap design and flap closure and the use of antibiotics and corticosteroids. This article discusses the special significance of modifying factors upon the incidence of perioperative complications associated with third molar surgery.

Acid-activatable cysteine proteinases in the cellular slime mold Dictyostelium discoideum.

Studies of the cysteine proteinases of the cellular slime mold Dictyostelium discoideum have been aided by a simple acid treatment step that was incorporated into the standard one-dimensional gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis assay procedure. The step involved immersing the separating gel in 10% (v/v) glacial acetic acid for 30-60 s immediately after electrophoresis. This modified approach revealed the presence of acid-activatable forms of some enzymes with noticeable increases in their ability to hydrolyze gelatin, a substrate present in the sodium dodecyl sulfate-polyacrylamide gels, and peptidyl amidomethylcoumarins. The activation has been analyzed using extracts of dormant spores from which cysteine proteinase activity had previously appeared low or virtually absent. The major acid-activatable proteinase had an apparent molecular mass of 48 kDa. Its activation was not due to autocatalysis as it was not prevented by mercuric chloride, an inhibitor of the enzyme, and was not accompanied by a significant change in electrophoretic mobility. It was most likely due to a conformational change and/or the removal of a low molecular weight inhibitor. The acid treatment has also revealed the presence of acid-activatable cysteine proteinases in vegetative cells, in which cysteine proteinase activity is present at high levels, as well as among enzymes from the developmental cells which have much lower cysteine proteinase activity. Indeed novel developmental forms were detected at some stages. These results provide additional insight concerning cysteine proteinase expression at various stages during development in the slime molds. A developmental model is presented which suggests that the crypticity of the cysteine proteinases in dormant spores may be governed by proton pumps and endogenous lysosomotropic agents.