Structural and antigenic polymorphism of the 35- to 48-kilodalton merozoite surface antigen (MSA-2) of the malaria parasite Plasmodium falciparum.

Merozoite surface antigen MSA-2 of the human parasite Plasmodium falciparum is being considered for the development of a malaria vaccine. The antigen is polymorphic, and specific monoclonal antibodies differentiate five serological variants of MSA-2 among 25 parasite isolates. The variants are grouped into two major serogroups, A and B. Genes encoding two different variants from serogroup A have been sequenced, and their DNA together with deduced amino acid sequences were compared with sequences encoded by other alleles. The comparison shows that the serological classification reflects differences in DNA sequences and deduced primary structure of MSA-2 variants and serogroups. Thus, the overall homologies of DNA and amino acid sequences are over 95% among variants in the same serogroup. In contrast, similarities between the group A variants and a group B variant are only 70 and 64% for DNA and amino acid sequences, respectively. We propose that the MSA-2 protein is encoded by two highly divergent groups of alleles, with limited additional polymorphism displayed within each group.

A comparison of the biochemical activities of Bacteroides corrodens and Eikenella corrodens with those of certain other gramnegative bacteria.

Tests carried out on strictly anaerobic and facultatively anaerobic strains of "corrodens" bacteria, showed that although these organisms are relatively inactive biochemically, differentiation can be made on the basis of tests that demonstrate reduction of nitrite, hydrolysis of urea and 1-naphthyl acetate, decarboxylation of lysine and ornithine, and sensitivity to certain selective agents included in culture medium. Plasma was found to be superior to serum in supporting the growth of all "corrodens" bacteria, and a combination of heated and unheated blood added to a nutrient base was shown to yield good growth. Comparative studies are reported with various species of Bacteroides, Haemophilus, Bordetella and related genera.

Finding the missing information in cancer statistics.

The current cancer literature is imprecise and confusing. This hampers the ability to draw meaningful conclusions regarding diagnosis and treatment. It is suggested that all future reporting of statistics contain the following features: (1) discussion of case selection criteria; (2) use of TNM system for case classification; (3) listing of minimal treatment details; (4) explanation for length of follow-up used; (5) standardized terms for evaluation (relating these to individual TNM classification); and (6) listing of all failures by standardized terms. It is proposed that editors of journals and organizers of meetings reject all papers that do not meet these criteria.

Microhabitat selection as an antipredator strategy in the aquatic insect Pachydiplax longipennis Burmeister (Odonata: Libellulidae).

An investigation of the larval dragonfly fauna associated with the plant, Sagittaria platyphylla, was conducted in a small pond. Despite the presence of several larval anisopteran species in the pond, only Pachydiplax longipennis larvae were found on Sagittaria plants. A study of the microspatial distribution of P. longipennis larvae on S. platyphylla indicated that larvae use the various regions of a plant in a highly non-random fashion. Larvae show a strong preference for the leaf axil area. A generalized predator, the bluegill sunfish (Lepomis macrochirus), was allowed to selectively eat either of two larvae placed in various plant regions. This experiment indicated that larvae in a leaf axil area were significantly less susceptible to bluegill predation than larvae positioned in other plant regions. The microspatial distribution of starved larvae revealed that larvae with high hunger levels occupied the leaf axil area significantly less than well fed larvae, suggesting 1) larvae do not use these regions as feeding sites, and 2) high hunger levels may induce a behavioral shift in habitat use, with starved larvae forced into areas of high predation risk by the need to fulfill nutritional requirements.

The controlled assembly of microcosmic communities: the selective extinction hypothesis.

Forty communities were assembled through the controlled inoculation of algae, protozoans and a rotifer according to either of 2 distinct introduction schedules. These introduction schedules were constructed such that species reinvaded on average either every 6 or 8 w. Ten of the 20 beakers experiencing each invasion schedule contained 300 ml of media; the remaining beakers in each invasion category contained 100 ml of media. Species richness consistently increased throughout the initial 4 w and 7 w of the experiment for the low and high invasion rate beakers, respectively. The numbers of species in the low rate beakers were uncorrelated with time during the last half of the experiment; however, species richness gradually declined during this period in the high rate beakers. The extinction rate is shown to be disproportionately higher for large organisms in the small microcosms. Such "selective extinction" is consistent with the MacArthur-Wilson equilibrium model.

The dilemma of the second surgeon.

The dilemma of the second surgeon is created when a patient is seen who has received advice and/or treatment by a colleague in the same specialty. The problem is compounded when conflicting opinions as to diagnosis, treatment, and results occur. This is discussed in the context of providing optimal care, maintaining effective communication, and avoiding the obvious pitfalls.

Facial nerve repair in cerebellopontine angle surgery.

Facial nerve continuity was restored during cerebellopontine angle tumor removal in nine cases. The distal facial nerve was rerouted from the stylomastoid foramen into the cerebellopontine angle. Direct suture was accomplished in seven cases while two required interposition of a greater auricular nerve graft. There was excellent return of facial function in eight of the nine cases. Overall results are superior to nerve substitution techniques. The facial nerve should be inspected for continuity following tumor removal. If one is not certain the nerve is intact, the proximal facial stump should be identified at the brain stem and facial nerve continuity reestablished. A nerve substitution procedure should be resorted to a later time only when the proximal facial stump is not identifiable.

Efficacy of Bacillus thuringiensis var. israelensis against larvae of the southern buffalo gnat, Cnephia pecuarum (Diptera: Simuliidae), and the influence of water temperature.

Susceptibility of southern buffalo gnat larvae to Bacillus thuringiensis var. israelensis (B.t.i.) was studied during 1986-88. Tests were conducted using Vectobac 12AS in a mini-gutter aquatic bioassay system. Mini-gutter tests using a 4.5 ppm B.t.i. concentration and a 10 min exposure period confirmed a positive correlation between water temperature and B.t.i. effectiveness. Significantly lower larval mortality occurred as water temperature decreased below 9 degrees C, indicating that proper timing of B.t.i. application is essential to maximize larval control. Even with this temperature limitation, larval control using B.t.i. should provide an economically effective means of preventing outbreaks of the southern buffalo gnat.

In vitro susceptibility of Bacteroides corrodens and Eikenella corrodens to ten chemotherapeutic agents.

Forty strains of Bacteroides corrodens and Eikenella corrodens were tested to determine their degree of susceptibility to 10 commonly prescribed chemotherapeutic agents. Significant differences were evident between strictly anaerobic strains and facultatively anaerobic strains.

Some observations on the effects produced in white mice following the injection of certain suspensions of corroding bacilli.

Strictly anaerobic and facultatively anaerobic strains of "corroding bacilli" failed to produce any pathological symptoms when injected into white mice and no viable organisms could be recovered after 7 days. However, when these same strains were coupled with certain other living bacteria or certain sterile bacterial extracts, lesions developed from which corroding bacilli could be isolated even after 21 days.

Intravenous histamine in otologic practice. Side effects in 2,347 administrations.

Intravenous (IV) histamine has been used extensively at the Otologic Medical Group, Inc, Los Angeles, for 30 years in the treatment of various conditions in which vasospasm was thought to play a part in the cause. We report the findings on 2,347 IV histamine administrations to 622 patients during a 33-month period. Dizziness was the indication for treatment in half of the patients. Sensorineural hearing impairments was the diagnosis in an additional 44%, and the majority of these had had a sudden impairment. Side effects were uncommon, never serious, and bore no relationship to the results of the histamine skin test or the patient's general medical problem. The IV histamine treatment resulted in improvement in symptoms in 36%, and almost half of those improvements were immediate.

Phylogenetic relationships of North American damselflies of the genus Ischnura (Odonata: Zygoptera: Coenagrionidae) based on sequences of three mitochondrial genes.

Relationships of North American damselflies of the genus Ischnura (Odonata: Zygoptera: Coenagrionidae) were investigated using a total of 1205 bp from portions of three mitochondrial genes: cytochrome b, cytochrome oxidase II, and 12S ribosomal DNA. Parsimony and neighbor joining analyses reveal a monophyletic group consisting of I. damula, I. demorsa, I. perparva, I. posita posita, I. posita atezca, I. verticalis, and probably I. denticollis, likely reflecting a recent radiation in North America. Ischnura kellicotti, I. barberi, I. prognata, I. hastata, I. ramburii, and I. capreola appear to represent much earlier divergences in the group. Many previous hypotheses of relationships among North American species of Ischnura are not supported by the molecular-based analyses. However, there is agreement in many respects between the results of the molecular phylogenetic analyses and the morphologically based conclusions of Kennedy (1919, "The Phylogeny of the Zygoptera," Ph.D. Dissertation, Cornell University, Ithaca). Although results of single-gene phylogenetic analyses often differ, there are very few cases in which there is strong support for conflicting relationships using different partitions of the data. Combined analysis of all three genes yields trees with stronger support overall than the single-gene analyses, and the combined data trees that result from diverse data treatments are congruent with one another in most respects.