Student-selected components: bringing more ENT into the undergraduate curriculum

Exposure to otolaryngology is currently minimal in the UK undergraduate medical curriculum. This may lead to difficulties in attracting graduates into higher ENT surgical training and in ensuring a reasonable standard of ENT knowledge amongst primary care practitioners.

A recent innovation, of which many ENT units may be unaware, is the introduction to the undergraduate curriculum of ‘student-selected components’. Like the traditional elective, this allows students to undertake an attachment to a speciality and department of their choice. Units which do not regularly teach medical students but which have a welcoming and enthusiastic approach to undergraduate training may well be ideal hosts.

This paper introduces the concepts underlying student-selected components, outlines the preparation required and offers a template for such an attachment, for which ENT is ideally suited.

Molecular cloning of Aspergillus fumigatus CgrA, the ortholog of a conserved fungal nucleolar protein

In this report we describe the cloning of cgrA, the Aspergillus fumigatus ortholog of the yeast nucleolar protein Cgr1p. The cgrA complementary DNA (cDNA) contains a single open reading frame that would encode a protein of 114 amino acids that has 42% sequence identity to yeast Cgrlp. Heterologous expression of a green fluorescent protein (GFP)-tagged A. fumigatus cgrA gene demonstrated that the CgrA protein could localize to the yeast nucleolus. Moreover, the cgrA cDNA complemented the growth deficiency caused by inducible depletion of intracellular Cgr1p levels in yeast. These results support an orthologous relationship between the CgrA and Cgr1 proteins, and open the way for future studies into the potential value of nucleolar proteins as antifungal targets.

Identification of genes of Aspergillus fumigatus up-regulated during growth on endothelial cells

Aspergillus fumigatus is an important opportunistic fungal pathogen that can cause acute invasive disease in neutropenic hosts. Invasive aspergillosis is being diagnosed with increasing frequency, and morbidity and mortality remain high despite prompt antifungal therapy. Because little is known about the virulence factors used by A. fumigatus, a tissue culture model was developed to mimic the interaction of the fungus with the endothelium. Differential display was used to compare gene expression in fungal cells grown on endothelial cells with that of cells grown in the absence of endothelial cell contact, and genes that were up-regulated were selected for analysis as putatively virulence-related genes. Two of these up-regulated genes were chosen for further study and were identified as genes encoding the regulatory subunit of cyclic adenosine monophosphate (cAMP)-dependent protein kinase and a member of the ras gene family, both of which are involved in cAMP-mediated signaling in fungi. This model system provides a new approach to the identification of potentially virulence-related genes induced in A. fumigatus by the interaction with host cells.

Molecular cloning of cgrA, the gene encoding the Aspergillus nidulans ortholog of Saccharomyces cerevisiae CGR1

Saccharomyces cerevisiae CGR1 encodes a 120-amino acid protein with a predominant nucleolar localization. In this study we report the identification and cloning of the ortholog, cgrA, from Aspergillus nidulans. The cgrA gene is comprised of three exons on A. nidulans Chromosome 7. The cDNA contains a single open reading frame (ORF) that would encode a protein of 114 amino acids with 44% sequence identity to yeast Cgr1p. A plasmid expressing cgrA complemented the impaired growth phenotype of a yeast strain that can be inducibly depleted of CGR1, and a green fluorescent protein (GFP)-tagged CgrA protein had the same nucleolar localization as the corresponding yeast protein. These results identify cgrA as the A. nidulans ortholog of yeast CGR1 and suggest evolutionary conservation of nucleolar localization mechanisms used by these proteins.

Cgr1p, a novel nucleolar protein encoded by Saccharomyces cerevisiae orf YGL0292w

Saccharomyces cerevisiae open reading frame (ORF) YGL029w (CGR1) encodes a small hydrophilic protein of unknown function. To investigate the role of this gene, we have determined the intracellular localization of the encoded product and examined the effects of Cgr1p depletion on cell growth. Tagging Cgr1p with the green fluorescent protein (GFP) or the myc epitope showed focal accumulation of the fusion protein in the yeast nucleolus, and this localization overlapped with the distribution of the nucleolar protein Nop1p. Cells depleted of CGR1 mRNA were growth impaired and hypersensitive to the translational inhibitor paromomycin, and this phenotype was complemented by episomal expression of the CGR1-GFP fusion gene. These results identify Cgr1p as a novel component of the yeast nucleolus and suggest a potential role in ribosome biogenesis.

Patient satisfaction with results of hysterectomy

OBJECTIVE

The objectives of this study were to measure patient satisfaction with the results of hysterectomy and to determine factors associated with dissatisfaction.

STUDY DESIGN

A total of 1299 women who underwent hysterectomy at 28 hospitals in Maryland were interviewed before and at 3, 6, 12, 18, and 24 months after the operation.

RESULTS

At 12 and 24 months after the hysterectomy 95.8% and 96.0%, respectively, reported that the hysterectomy had completely or mostly resolved the problems or symptoms they had before surgery; 93.3% and 93.7%, respectively, reported that the results were better than or about what they expected; 85.3% and 81. 6%, respectively, reported that their health was better than before the hysterectomy; and 87.9% and 93.1%, respectively, reported being totally recovered. The factor most strongly and consistently associated with patient reports of negative outcomes was readmission because of a postdischarge complication.

CONCLUSION

Postdischarge complication necessitating readmission plays an important role in patient dissatisfaction with the results of hysterectomy.

Effectiveness of hysterectomy

OBJECTIVE

To measure the effectiveness of hysterectomy in relieving adverse symptoms and to identify factors associated with lack of symptom relief.

METHODS

In a 2-year prospective study, data were collected before and at 3, 6, 12, 18, and 24 months after hysterectomy in 1,299 women who had hysterectomies for benign conditions at 28 hospitals across Maryland. Effectiveness was measured in terms of relief of symptoms such as problematic vaginal bleeding, pelvic pain, and urinary incontinence. Psychologic function and quality of life before and after surgery also were assessed.

RESULTS

Symptom severity, depression, and anxiety levels decreased significantly after hysterectomy and quality of life improved, particularly in the area of social function. However, 8% of women had at least as many symptoms at problematic-severe levels 1 and 2 years after hysterectomy as before. In multiple logistic regression, several presurgical patient characteristics predicted lack of symptom relief, including therapy for emotional or psychologic problems, depression, and household income of $35,000 or less. Bilateral oophorectomy predicted lack of symptom relief at 24 months but not at 12 months after hysterectomy.

CONCLUSION

Significant improvements were seen after hysterectomy for all three aspects of health status (symptoms, psychologic function, and quality of life), which persisted or continued to improve throughout the 2 years of follow-up. However, hysterectomy did not relieve symptoms for some women, particularly those who had low incomes or were in therapy at the time of hysterectomy.

Ovarian volume and menopausal status

OBJECTIVE

The purposes of this study were to (1) examine whether ovarian volume differs by age and menopausal status in healthy women; (2) evaluate whether ovarian volume could be a sensitive and specific predictor of menopausal status; and (3) assess whether ovarian volume is affected by cigarette smoke, oral contraceptives (OCs), and hormone replacement therapy (HRT).

DESIGN

Each participant (527 women) completed an extensive in-home interview that assessed age, menopausal status, smoking history, OC use, and HRT use. Each participant also received a transvaginal ultrasound that measured ovarian volume. Geometric means for ovarian volume were compared between premenopausal and postmenopausal women using t tests. Tests for trends were conducted using linear regression analyses.

RESULTS

Ovarian volume declined with age (p < or = 0.0001) and also differed by menopausal status; postmenopausal women had smaller ovarian volumes than premenopausal women of the same age (p < or = 0.0001). Ovarian volume was not associated with smoking history or HRT use. However, it was significantly smaller in current users of OCs compared with past users of or those who never used OCs (p < or = 0.0001). Ovarian volume was a sensitive and specific predictor of postmenopausal status.

CONCLUSIONS

The data suggest that age, menopausal status, and OC use may be determinants of ovarian volume. They also suggest that ovarian volume may be useful for predicting menopausal status in women.

Hysterectomy and sexual functioning

CONTEXT

Women considering hysterectomy often are concerned about its potential effects on their sexual functioning but the effects of hysterectomy on sexual functioning remain unclear.

OBJECTIVE

To examine changes in sexual functioning after hysterectomy.

DESIGN AND SETTING

A 2-year prospective study (Maryland Women's Health Study) of hysterectomy, which included measures of sexual functioning prior to hysterectomy and at 6, 12, 18, and 24 months after hysterectomy, performed during 1992 and 1993.

PATIENTS

Of 1299 women interviewed prior to hysterectomy, 1101 (84.8%) completed the study and provided information about their sexual functioning. Most were between the ages of 35 and 49 years, white, married or living with a partner, and high school graduates.

MAIN OUTCOME MEASURES

Frequency of sexual relations, dyspareunia, orgasm, vaginal dryness, and sexual desire.

RESULTS

The percentage of women who engaged in sexual relations increased significantly from 70.5% before hysterectomy to 77.6% and 76.7% at 12 and 24 months after hysterectomy. The rate of frequent dyspareunia dropped significantly from 18.6% before hysterectomy to 4.3 % and 3.6% at 12 and 24 months after hysterectomy. The rates of not experiencing orgasms dropped significantly from 7.6% before hysterectomy to 5.2% and 4.9% at 12 and 24 months after hysterectomy. Low libido rates also decreased significantly from 10.4% before hysterectomy to 6.3% and 6.2% at 12 and 24 months after hysterectomy. The distribution of women not reporting vaginal dryness in the past month improved significantly from 37.3% before hysterectomy to 46.8% and 46.7% at 12 and 24 months after hysterectomy. Prehysterectomy depression was associated with experiencing dyspareunia, vaginal dryness, low libido, and not experiencing orgasms after hysterectomy.

CONCLUSIONS

Sexual functioning improved overall after hysterectomy. The frequency of sexual activity increased and problems with sexual functioning decreased.

Utility of routine testing of bronchoalveolar lavage fluid for cryptococcal antigen

All cryptococcal antigen (CrAg) testing performed at our institution between 1989 and 1994 was reviewed for utility of routinely testing of bronchoalveolar lavage fluid (BAL) for this antigen. Forty-two of 1,506 BAL specimens were positive. Seventeen of these were felt to represent false positives (sensitivity, 71%; positive predictive value, 0.59). The data on CrAg in cerebrospinal fluid and serum and the fungal culture and histological results of BAL specimens did not support continued, routine testing of BALs for CrAg to diagnose cryptococcosis.

Sequencing of a gene encoding a member of the mitochondrial carrier family of transport proteins from Aspergillus nidulans

Mitochondrial carrier proteins comprise a superfamily of evolutionarily conserved proteins that regulate the specific transport of essential metabolites across the mitochondrial membranes. In this report we describe the cloning and sequencing of a gene from Aspergillus nidulans, amc-1, that encodes the first reported example of a mitochondrial carrier protein in Aspergillus species. The amc-1 gene is located on chromosome 7, and is transcribed as a 1.6 kb unspliced polyadenylated RNA. The predicted translation product of the amc-1. cDNA displays three tandemly repeated domains which possess protein signature motifs that are characteristic of mitochondrial carrier proteins that localize to the inner mitochondrial membrane. amc-1 shares the greatest similarity with a Neurospora mitochondrial carrier protein that is implicated in basic amino acid transport, suggesting that the amc-1 protein may provide a related function.

Characterization of a putative retroviral env-related human protein

In this study, we developed a rabbit polyclonal antibody to a fusion protein containing the envelope (env) transmembrane (TM) region from the human endogenous retroviral family, HERV-E. We used this reagent to document the expression of TM-related protein by Western blot in endothelial, colon and prostate carcinoma and seminoma cell lines and in peripheral blood mononuclear cells from a healthy donor. We detected a 58-kD protein (as compared to murine TM of 15 kD) that had specificity for the env-related antibodies of the polyclonal antiserum.

Evolutionary conservation of putative functional domains in the human homolog of the murine His-1 gene

The mouse His-1 gene encodes a spliced and polyadenylated RNA with no long open reading frame (ORF), making it difficult to distinguish a functional protein coding domain. To identify candidate protein coding ORFs, and other functionally significant regions, we have isolated and sequenced 8.5 kb of a human genomic DNA that is homologous to the mouse His-1 gene. Alignment of the mouse and human sequences required no extensive gapping, indicating that evolutionary constraints have maintained a requirement for colinearity in genomic organization. We have identified the mouse transcriptional start point (tsp) and shown that the sequence of the 5'-flanking region is highly conserved in the human homolog. Sequence comparisons between the mouse and human genes identified conservation of other putative functional domains in exon 3 and in each of the two introns. Southern blot analysis with probes from each of these regions detected homologs in multiple other vertebrate species. However, none of the multiple candidate ORFs in the mouse RNA were conserved in the human sequence, suggesting that the RNA is unlikely to encode a protein. These data suggest that the RNA may be the final and functional product from the mouse His-1 gene.

The chsD and chsE genes of Aspergillus nidulans and their roles in chitin synthesis

Two chitin synthase genes, chsD and chsE, were identified from the filamentous ascomycete Aspergillus nidulans. In a region that is conserved among chitin synthases, the deduced amino acid sequences of chsD and chsE have greater sequence identity to the polypeptides encoded by the Saccharomyces cerevisiae CHS3 gene (also named CSD2, CAL1, DIT101, and KTI1) and the Candida albicans CHSE gene than to other chitin synthases. chsE is more closely related to the CHS3 genes, and this group constitutes the class IV chitin synthases. chsD differs sufficiently from the other classes of fungal chitin synthase genes to constitute a new class, class V. Each of the wild-type A. nidulans genes was replaced by a copy that had a substantial fraction of its coding region replaced by the A. nidulans argB gene. Hyphae from both chsD and chsE disruptants contain about 60-70% of the chitin content of wild-type hyphae. The morphology and development of chsE disruptants are indistinguishable from those of wild type. Nearly all of the conidia of chsD disruption strains swell excessively and lyse when germinated in low osmotic strength medium. Conidia that do not lyse produce hyphae that initially have normal morphology but subsequently lyse at subapical locations and show ballooned walls along their length. The lysis of germinating conidia and hyphae of chsD disruptants is prevented by the presence of osmotic stabilizers in the medium. Conidiophore vesicles from chsD disruption strains frequently swell excessively and lyse, resulting in colonies that show reduced conidiation. These properties indicate that chitin synthesized by the chsD-encoded isozyme contributes to the rigidity of the walls of germinating conidia, of the subapical region of hyphae, and of conidiophore vesicles, but is not necessary for normal morphology of these cells. The phenotypes of chsD and chsE disruptants indicate that the chitin synthesized by each isozyme serves a distinct function. The propensity of a chsD disruptant for osmotically induced lysis was compared to that of strains carrying two other mutations (tsE6 and orlA::trpC) which also result in reduced chitin content vegetative cell lysis. The concentration of osmotic stabilizer necessary to remedy the lysis of strains carrying the three mutations is inversely related to the chitin content of each strain. This finding directly demonstrates the importance of chitin to the integrity of the cell wall and indicates that agents that inhibit the chsD-encoded chitin synthase could be useful anti-Aspergillus drugs.

Expression of a putative immunosuppressive protein in human tumors and tissues

Tumor-induced immunosuppression by murine retrovirus-induced tumors and nonviral murine and human tumors has been shown to be mediated by the transmembrane (TM) envelope (env) protein p15E. This in vitro activity is inhibitable by anti-(murine)p15E antibodies, implying that a TM-like protein is produced by such tumors. The leading candidate genes that might encode such proteins in human tumors are human endogenous retroviral (HERV) sequences. We have utilized immunohistochemistry to determine what tissues may express HERV env proteins. We subcloned a restriction fragment from the putative TM human env gene of a type C-related HERV (clone-4-1) into a fusion protein gene construct. Using a rabbit polyclonal antiserum against the fusion protein, we observed staining in a variety of human tumor and nontumor tissues.

Phaeohyphomycosis caused by Dactylaria (human dactylariosis): report of a case with review of the literature

Phaeohyphomycosis due to Dactylaria (Ochroconis) spp. is a rare infection of man. It was first reported in 1986. All patients have had significant immunosuppression. To our knowledge, this is the second case of phaeohyphomycosis caused by Dactylaria constricta var. gallopava in a liver transplant patient and it developed even though he had been receiving fungal prophylaxis with fluconazole. Moreover, this case may represent nosocomial acquisition. In addition, we have reviewed the English language literature of previously reported patients with phaeohyphomycosis caused by Dactylaria spp.

Near-isogenic lines of maize differing for glycinebetaine

A series of near-isogenic glycinebetaine-containing and -deficient F8 pairs of Zea mays L. (maize) lines were developed. The pairs of lines differ for alternative alleles of a single locus; the wild-type allele conferring glycinebetaine accumulation is designated Bet1 and the mutant (recessive) allele is designated bet1. The near-isogenic lines were used to investigate whether glycinebetaine deficiency affects the pool size of the glycinebetaine precursor, choline, using a new method for glycinebetaine and choline determination: stable isotope dilution plasma desorption mass spectrometry. Glycinebetaine deficiency in maize was associated with a significant expansion of the free choline pool, but the difference in choline pool size was not equal to the difference in glycinebetaine pool size, suggesting that choline must down-regulate its own synthesis. Consistent with this, glycinebetaine deficiency was also associated with the accumulation of the choline precursor, serine. A randomly amplified polymorphic DNA marker was identified that detects the bet1 allele. In 62 F8 families tested the 10-mer primer 5'-GTCCTCGTAG produced a 1.2-kb polymerase chain reaction product only when DNA from Bet1/bet1 or bet1/bet1 lines was used as template. All 26 homozygous Bet1/Bet1 F8 families tested were null for this marker.

Detection of cryptococcal antigen in bronchoalveolar lavage fluid: a prospective study of diagnostic utility

Cryptococcal pneumonia is associated with significant morbidity and mortality in immunocompromised patients. We examined the utility of screening bronchoalveolar lavage (BAL) fluid for cryptococcal antigen. In a pilot study, we found that cryptococcal antigen was always positive in unprocessed BAL specimens of seven patients with cryptococcal pneumonia and negative in 44 patients with other granulomatous diseases who acted as the control subjects. A prospective study was done of 220 immunocompromised patients (188 with human immunodeficiency virus infection, 32 with other causes of immunosuppression) undergoing BAL for fever and pulmonary symptoms. The eventual diagnosis of cryptococcal pneumonia was made in eight patients. All eight patients had a cryptococcal antigen titer greater than or equal to 1:8. There were four patients without cryptococcal pneumonia who had cryptococcal antigen titers of 1:8, there were none with higher titers. For a titer of cryptococcal antigen titer of greater than or equal to 1:8, there was 100% sensitivity, 98% specificity, a positive predictive value of 67%, and a negative predictive value of 100%. The measurement of cryptococcal antigen in the BAL can be a rapid, simple way to make a diagnosis of cryptococcal pneumonia in immunosuppressed patients with pneumonia.

Elevated Accumulation of Proline in NaCl-Adapted Tobacco Cells Is Not Due to Altered Delta-Pyrroline-5-Carboxylate Reductase

Tobacco (Nicotiana tabacum L. var Wisconsin 38) cells that are adapted to 428 millimolar NaCl accumulate proline mainly due to increased synthesis from glutamate. These cells were used to evaluate the possible role of Delta(1)-pyrroline-5-carboxylate reductase in the regulation of proline biosynthesis. No increase in the specific activity of Delta(1)-pyrroline-5-carboxylate reductase in crude extracts throughout the growth cycle was observed in NaCl-adapted cells compared to unadapted cells. The enzyme from both cell types was purified extensively. On the basis of affinity for the substrates NADPH, NADH, and Delta(1)-pyrroline-5-carboxylate, pH profiles, chromatographic behavior during purification, and electrophoretic mobility of the native enzyme, the activities of the enzyme from the two sources were similar. These data suggest that the NaCl-dependent regulation of proline synthesis in tobacco cells does not involve induction of pyrroline-5-carboxylate isozymes or changes in its kinetic properties.

Isolation and characterization of an elastinolytic proteinase from Aspergillus flavus

An elastinolytic proteinase of Aspergillus flavus has been isolated to homogeneity, and its physical and biochemical properties have been characterized. Two purification protocols were compared; an initial step of ion-exchange chromatography was found to be equivalent to ammonium sulfate precipitation at neutral pH. A combination of gel filtration and adsorption chromatographies on the resultant crude enzyme produced highly purified elastase with yields of 5 to 10%. The enzyme is a 23-kilodalton protein with a pI of 7.6. The enzyme activity is markedly inhibited by numerous metal ions. Aspergillus elastase appears to be a metalloproteinase EC 3.4.24.X), as determined by its sensitivity to 1,10-phenanthroline.

Experimental murine invasive pulmonary aspergillosis

A new model of invasive pulmonary aspergillosis (IPA) was developed in immunosuppressed mice. Intranasal route of inoculation was used to deliver predictable numbers of Aspergillus flavus conidia. The LD50 was determined to be 2.7 X 10(2) viable conidia, and a combination of quantitative culture and determination of chitin content was shown to best measure the progression of pulmonary disease. The evolution of IPA in these mice conformed with what has been reported in human cases of aspergillosis; both histopathology of the pulmonary lesions and dissemination pattern resembled their human counterparts. The authors hope to use this model to study virulence mechanisms of Aspergillus and novel therapeutic methods.

Development of two isogenic sweet corn hybrids differing for glycinebetaine content

A hybrid of sweet corn, Zea mays L. (;1720'; Rogers Brothers Seed Co.), was found to be comprised of glycinebetaine-positive and glycinebetaine-deficient individuals in a 1:1 mixture. This phenomenon was traced to segregation for a single, nuclear, dominant gene determining leaf glycinebetaine content within the female inbred parent of this hybrid. Selection for homozygous recessive (glycinebetaine-deficient) and homozygous dominant (glycinebetaine-positive) genotypes of the female inbred parent enabled production of two isogenic versions of hybrid ;1720' differing with respect to a single copy of the dominant allele, by mating these female parent selections with the common homozygous recessive (glycinebetaine-deficient) male parent. These two isogenic hybrids are shown to differ by a factor of 300- to 400-fold in glycinebetaine titer of young expanding leaves of salinized plants, but exhibit no striking differences in the levels of free amino acids or the level of N-methylnicotinic acid (nicotinic acid betaine; trigonelline). The only significant difference between the two hybrids in terms of amino acid composition was found to be in the level of alanine under nonsalinized conditions. The betaine-deficient hybrid exhibited a 14% lower alanine level than the betaine-positive hybrid. Betaine deficiency was not associated with altered stress-induced accumulation of amino acids such as proline, serine, and asparagine plus aspartate, attesting to the high specificity of the genetic difference between these isogenic hybrids with respect to betaine accumulation. This germplasm offers unique opportunities to test whether a single dominant allele determining stress-induced betaine accumulation capacity influences stress resistance in maize.

Virulence factors in fungal pathogens

Fungal pathogens possess virulence factors that allow them to cause disease in humans and animals. Combinations of properties such as temperature tolerance, evasion of host defences, dimorphism, and enzymatic activities may serve as virulence mechanisms for fungi.

Elastase production in clinical isolates of Aspergillus

Clinical isolates of Aspergillus species were tested, both retrospectively and prospectively, for elastase activity using rose bengal-elastin agar plates. Patient records were then reviewed to determine the clinical diagnosis including the presence or absence of aspergillosis. All isolates that caused invasive aspergillosis produced elastase, but not all isolates producing elastase were associated with invasive disease.

Paecilomyces variotii. An unusual cause of isolated sphenoid sinusitis

Isolated fungal sphenoid sinusitis is an unusual head and neck infection. We describe the first reported case (to our knowledge) of Paecilomyces variotii sphenoid sinusitis. In addition, it represents one of the few reported cases of isolated fungal sphenoid sinusitis. Diagnosis and management of this condition are described. Aggressive surgical management is advocated when fungal sphenoid sinusitis is suspected.

Encapsulation and melanin formation as indicators of virulence in Cryptococcus neoformans

Acapsular (Cap-) mutants of Cryptococcus neoformans var. neoformans that produce melanin (Mel+) on diphenol media at 30 degrees C but not at 37 degrees C were found to be avirulent for mice. Compared with wild-type isolates, the mutants had a lower rate of L-3,4-dihydroxyphenylalanine uptake at 37 degrees C and showed an insignificant level of phenoloxidase activity at both temperatures. To study the relationship of Cap and Mel phenotypes to virulence in mice, we crossed one of the mutants (Cap- Mel-) with a wild type (Cap+ Mel+) to obtain four classes of progeny (Cap+ Mel+, Cap+ Mel-, Cap- Mel+, and Cap- Mel-). The progeny with the Cap+ Mel+ phenotype and the wild-type parent (Cap+ Mel+) were inoculated into mice (10(6) cells per mouse) and, within 40 days, produced fatal infection in 90 to 100% of the animals. None of the other three phenotypes produced fatal infection within the same period. While progeny with the Cap+ Mel- phenotype did produce fatal infection after 40 days, 70 to 90% of the mice survived at least until day 70. However, in the isolates recovered from the brain tissue of a mouse that died on day 68, nearly 40% of the CFU had reverted to the Cap+ Mel+ type. The virulence of one of these revertant Cap+ Mel+ isolates was compared with that of a Cap+ Mel- isolate recovered from the same tissue. One hundred percent of the mice inoculated with the revertant died within 35 days, while no fatal infection was produced in the mice inoculated with the Cap+ Mel- isolate within the same period. The isolates with the Cap- Mel+ or Cap- Mel- phenotype not only failed to produce fatal infection but failed to revert to the Cap+ Mel+ type in the mouse brain during the experimental period. These results indicate that both the Cap+ phenotype and the Mel+ phenotype are important indicators of virulence in C. neoformans.

Contribution of complement component C5 to the pathogenesis of experimental murine cryptococcosis

C5-deficient (C5-) mice succumb much sooner after intravenous inoculation with Cryptococcus neoformans than do C5-sufficient (C5+) mice. The C5- mice developed acute, fatal cryptococcal pneumonia, whereas the C5+ mice did not. The pneumonia was characterized by lung viable counts in C5- mice up to 1000-fold higher than in C5+, initial sequestration of twice as much 59Fe-labeled C. neoformans, and subsequent development of pulmonary edema. Chemotaxis of heterophils (PMNs) and mononuclear cells in response to C. neoformans was markedly greater in C5+ mice than in C5- animals. The effect of C5 on localization and growth of C. neoformans in the lung appeared to account for the disparate survival times of C5+ and C5+ mice after intravenous inoculation with C. neoformans.

Production and regeneration of protoplasts from Cryptococcus

Protoplasts were quickly and efficiently produced from both varieties of Cryptococcus neoformans and from C. laurentii by use of the multi-enzyme product Novozym 234. Conditions for regeneration of protoplasts are described. DNA yield from the Novozym-produced protoplasts was superior to that from snail gut enzyme-derived protoplasts.

Inhibition of antipyrine metabolite formation in rats in vivo

The effect of four inhibitors of cytochrome P-450-mediated drug oxidations (SKF 525A, cimetidine, metyrapone and alpha-naphthoflavone) on the urinary metabolite pattern and 14CO2 exhalation rate (CER)-time profile following [N-methyl-14C]antipyrine administration has been investigated. The CER-time profiles indicated that inhibition of antipyrine metabolism was in the rank order SKF 525A greater than cimetidine greater than metyrapone greater than ANF. The urinary metabolite patterns showed selectively in action towards particular pathways, 3-hydroxylation being primarily decreased by SKF 525A and cimetidine, and N-demethylation by ANF. The results provide further evidence for involvement of multiple forms of cytochrome P-450 in antipyrine metabolism.

Use of the rapid diazonium blue B test to differentiate clinically important species of Trichosporon and Geotrichum

Trichosporon isolates form pink to violet pigments following reaction with diazonium blue B which reliably differentiates them from Geotrichum species. The inoculum could be grown in static culture without diminishing the colour intensity. This modification facilitates use of the diazonium blue B reaction in clinical laboratories.

Antipyrine metabolite kinetics in rats: studies on dose and time dependence

Antipyrine metabolite kinetics have been investigated in the rat with respect to dose and time dependence. The metabolic pathways, 4-hydroxylation, benzylic oxidation, and N-demethylation, are of equal quantitative importance (approximately 20 per cent of dose) and show no dose dependence over the range 25-500 mg kg-1. By using [N-methyl-14C]-antipyrine, the single carbon fragment lost by N-demethylation may be monitored as 14CO2. Serial sampling of 14CO2 exhalation rate provides a half-life estimate which, according to theoretical principles, reflects the antipyrine plasma half-life. When both half-lives were measured in the same animals a statistically significant correlation was evident. At doses of 250 mg kg-1 and 500 mg kg-1 there is an increase in CER half-life (218 and 303 min respectively) when compared to a dose below 100 mg kg-1 (152 min). The metabolite formation rate constants are decreased accordingly at the high doses but are invariant over the dose range 25-100 mg kg-1. Although inter-rat variation in antipyrine metabolite kinetics was substantial, intra-rat variability was small. The noninvasive nature of determining antipyrine metabolite kinetics via breath and urine analysis provides a potentially useful animal model system to investigate the factors influencing hepatic mixed function oxidase activity in vivo.

Gonadal hormone regulation of MAO and other enzymes in hypothalamic areas

Activities of type A monoamine oxidase (MAO), acetylcholine esterase (AChE), and glucose-6-phosphate dehydrogenase (G6PDH) were differentially altered in hormone-sensitive areas of the preoptic-hypothalamic continuum after administration of estrogen and progesterone. Estrogen increased activity of AChE in the bed nucleus of the stria terminalis and activity of G6PDH in the periventricular area (PVE) of the preoptic area, arcuate-median eminence (Ar-ME) and pituitary. Estrogen decreased activity of MAO in the PVE of the anterior hypothalamus, pars lateralis of the ventromedial nucleus and in the Ar-ME. Acute administration of progesterone (1 h) to estrogen-treated females did not further alter estrogen-dependent changes in AChE or G6PDH; however, MAO activity in the ventromedial nucleus and Ar-ME was rapidly increased after progesterone. Without prior estrogen administration, progesterone did not affect MAO activity. Administration of the protein synthesis inhibitor anisomycin prior to progesterone did not antagonize progesterone-dependent increases in MAO. Progesterone added in vitro to homogenates from estrogen-treated but not from untreated females increased MAO activity. The hormonal specificity, time course of effects and anatomical location of the enzymatic changes suggest that some of them may participate in the mediation of gonadal hormone action in the CNS. In particular, changes in MAO activity in the ventromedial nucleus and Ar-ME are consistent with reported effects of these hormones on monoamine turnover which in turn have been suggested to contribute to hormonal regulation of feminine sexual behavior and gonadotropin secretion.

Interpretation of CO2 exhalation rate data from demethylation of aminopyrine and its metabolite monomethylaminoantipyrine

1 Aminopyrine breath tests make use of the commercially available (N-dimethyl-[14C])-aminopyrine. A pharmacokinetic model has been proposed to relate 14CO2 exhalation rates (CER) to the demethylation of ([14C]-methyl)-aminopyrine (AP) and -monomethylaminoantipyrine (MAP). 2 computer simulations based on the model show that the shape of the CER-time profile is largely dependent on the ratio of the MAP to AP elimination rate constants. If this ratio equals 0.5 then the CERs decline in the monoexponential fashion. Ratios less than 0.5 result in concave biexponential curves whereas ratios greater than 0.5 result in convex curves. When demethylation is not complete for both compounds the transfer from biexponential to monoexponential behaviour will only occur at ratios greater than 0.5. 3 The resolution of concave biexponential CER-time profiles to give accurate estimates of AP and MAP elimination rate constants can only be achieved when the length of the experiment is adequate. The commonly employed 2 microCi tracer dose of aminopyrine is insufficient to monitor CER over the necessary time period to detect the proposed biexponential decline.

Phenoloxidase activity and virulence in isogenic strains of Cryptococcus neoformans

A naturally occurring Mel- variant of Cryptococcus neoformans was isolated from the wild type. The effect of phenoloxidase activity on virulence was analyzed on genetically constructed Mel+ and Mel- isolates. The traits Mel+ and virulence in mice, as measured by cumulative mortality and replication potential in brain tissue, cosegregated among the progeny of a Mel+ X Mel- cross. Revertants (MelR) isolated during the course of the cumulative mortality experiment were used to compare virulence in isogenic sets of Mel- and MelR. In two separate sets of such isolates, Mel+ phenotype and virulence coreverted. Measurement of substrate uptake and phenoloxidase activity showed that loss of detectable phenoloxidase was the basis for the Mel- phenotype and that enzyme activity reappeared in the MelR isolates. An intermediate phenotype, Melbg, was also described. Cosegregation and coreversion of the melanin phenotype and virulence suggest that phenoloxidase is a virulence factor in C. neoformans.

Taxonomic studies on Filobasidiella species and their anamorphs

The taxonomy of Filobasidiella neoformans Kwon-Chung and F. bacillispora Kwon-Chung and their anamorphs were reinvestigated. Although the cross between the type culture of the two species failed to produce viable basidiospores, another pair of isolates did yield viable basidiospores. The segregation of phenotypic markers among the tetrads isolated from this inter specific cross proved that meiosis had occurred. On the basis of other previously known differences and the present genetic study, the two species are now considered to be two varieties of the species, F. neoformans. The anamorph of F. neoformans var. neoformans grew well at 37 degrees C in vitro and produced fatal infection in mice while that of F. neoformans var. bacillispora grew poorly at 37 degree C and failed to produce fatal infection in mice. Cryptococcus bacillisporus Kwon-Chung et Bennett is regarded as a synonym of C. neoformans var. gattii Vanbreuseghem et Takashio.

Ultrastructure of the septal complex in hyphae of Cryptococcus laurentii

Electron microscopy of hyphae produced by Cryptococcus laurentii revealed typical basidiomycetous dolipore septa between the cells. Parenthesomes were not observed.

Clinical evaluation of the AutoMicrobic system Yeast Biochemical Card for rapid identification of medically important yeasts

The autoMicrobic system Yeast Biochemical Card (Vitek Systems, Inc., subsidiary of McDonnell Douglas, Hazelwood, Mo.), a fully automated and computer-assisted method for identifying seven yeast genera based on 26 biochemical reactions, was compared with the API 20C (Analytab Products, Plainview, N.Y) yeast identification system, using 253 clinical yeast isolates. There was an 84% correlation between the Yeast Biochemical Card and API 20C systems based on biochemical tests alone and a 96% correlation when morphology was combined with the biochemical profile. Of 22 species examined, 14 were definitively identified within 24 h, using only the biochemical tests; the remaining 8 species were presumptively identified, using biochemical tests within 24 h, with definitive identification being completed in 48 to 72 h when morphological characteristics were ascertained. The Yeast Biochemical Card system was both a facile and, with concomitant morphology, an accurate system for performing yeast identification.

Quantification of naphthyl conjugates. Comparison of high-performance liquid chromatography and selective enzyme hydrolysis methods

1. An h.p.l.c. method for the simultaneous determination of naphthol, naphthyl glucuronide and naphthyl sulphate in urine is described. This procedure is based on the selective formation of an ion pair between the sulphate conjugate and tetrabutyl lammonium, which allows its resolution from the glucuronide on a reverse phase column. 2. The h.p.l.c. method is sed to assess the selective enzyme hydrolysis method which is frequently employed in drug conjugate assays. Results suggest that the use of sulphatase and beta-glucuronidase may give data which are quantitatively and qualitatively erroneous.

Genetic control of susceptibility to Cryptococcus neoformans in mice

Inbred mice injected intravenously with 5 x 10(6) cells of Cryptococcus neoformans showed two patterns of survival: sensitive (A/WySn, A.BY, A/J, DBA/2J, NZB/B1NJ, and SWR/J) and resistant [C57BL/10Sn, B10.A, B10.A (2R), B10.S (7R),C57BR/cdJ, C58/J, C3H/HeJ, BALB/c, DBA/1J, and SJL/J]. Relative susceptibility based on survival time was shown to correspond to differences obtained for 50% lethal dose values. Either decreasing the dose of organisms or changing to the intraperitoneal route of inoculation resulted in prolonged survival times, but neither change affected the observed patterns of survival. F1 hybrids between different sensitive strains were also sensitive, whereas F1 hybrids between sensitive and resistant strains were resistant, indicating a dominant mode of inheritance. Sensitivity and resistance were shown to be under single gene control by segregation analysis in F2 progeny produced by inbreeding (B10.A x A/WySn)F1 hybrids and in (F1 x A/WySn) backcross progeny. Blood obtained from parental strains, F1, F2, and backcross hybrids was tested for the presence or absence of hemolytic complement. Mice lacking hemolytic complement activity in their sera are homozygous for the Hc(0) allele at the Hc locus on chromosome 2 and are deficient in the complement component C5. A 1:1 correspondence was found between C5 deficiency and sensitivity to C. neoformans. Resistance was shown to cosegregate with the presence of hemolytic complement in the F2 and the backcross progenies.

Isolation and characterization of arginine auxotrophs of Cryptococcus neoformans

Arginine auxotrophs were isolated in both mating types of Cryptococcus neoformans. In both mutants, the auxotrophy was due to the lack of active argininosuccinate lyase. The virulence in mice of the mutants was compared with that of the wild type. One auxotroph displayed a loss of virulence which appeared to be related to the presence of another mutation, one which prevented normal cell separation after budding. The other auxotroph had reduced virulence compared with the wild type, but a variant isolated from it by mouse passage had virulence equivalent to that of the wild type while maintaining the auxotrophic requirements.

Comparison of four methods for determining nitrate utilization by cryptococci

This study evaluated the following methods for determining nitrate utilization: Wickerham broth, a special nitrate broth, Delft plate, and nitrate strip. With 236 isolates of cryptococci as test organisms, the special nitrate broth method gave 99% correct results and the Wickerham broth method gave 98%. The nitrate strip and Delft plate methods gave correct results in 94 and 86% of tests, respectively. The special nitrate broth method is judged superior because it provides accurate results within 48 h, compared to 14 days with the Wickerham broth method.