Outbreak of acute histoplasmosis in a family group: identification of the infection source

An outbreak of acute histoplasmosis occurring in 4 members of the same family, two women, a girl and a male, is reported. The index case presented acute respiratory symptoms, severe enough to require hospitalization. In the remaining persons, the infection was asymptomatic but was evidenced by reactive histoplasmin serologic tests. Search for the common source of infection led to an enriched soil obtained in a local nursery for growing in-door plants. BALB/c mice were inoculated with suspensions of soils from the potted plants. Histoplasma capsulatum var. capsulatum was isolated from various internal organs of the mice. Although histoplasmosis is observed more frequently in persons with occupations implying risk of exposure and is connected to rural areas, outbreaks and intra-family cases are now common in urban areas. This is due to massive urbanization, deforestation, demolitions and the use of soils enriched with organic compounds, mainly bird/bat excrements. This report calls the attention on the danger involved in using such enriched soils for plant nutrition.     

Geographical Differentiation of the Population of Xanthomonas axonopodis pv. manihotis in Colombia

[This corrects the article on p. 4430 in vol. 63.].     

Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands

The alpha3 fucosyltransferase, FucT-VII, is one of the key glycosyltransferases involved in the biosynthesis of the sialyl Lewis X (sLex) antigen on human leukocytes. The sialyl Lewis X antigen (NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential component of the recruitment of leukocytes to sites of inflammation, mediating the primary interaction between circulating leukocytes and activated endothelium. In order to characterize the enzymatic properties of the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been expressed in Trichoplusia ni insect cells. The enzyme is capable of synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from 3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors demonstrate that FucT-VII is able to synthesize both di-fucosylated and tri-fucosylated structures from mono- fucosylated precursors, but preferentially fucosylates the distal GlcNAc within a polylactosamine chain. Furthermore, the rate of fucosylation of the internal GlcNAc residues is reduced once fucose has been added to the distal GlcNAc. These results indicate that FucT-VII is capable of generating complex selectin ligands, in vitro , however the order of fucose addition to the lactosamine chain affects the rate of selectin ligand synthesis.      

The effect of salts on the kinetics of iron release from N-terminal and C-terminal monoferrictransferrins

The kinetics of iron release from N-terminal and C-terminal monoferric human transferrins has been studied using EDTA as the accepting chelate. In the absence of added salts iron release from the N-terminal site is more facile but the relative lability can be reversed by the addition of NaClO₄, NaCl and LiCl. The results indicate that both anions and cations can affect the lability of the two sites. Since the relative lability of the two monoferrictransferrins is affected by fairly moderate concentrations of NaCl and NaClO₄ we suggest that the ionic composition serum may play an important role in determining the observed distribution of iron among the sites. A new method for the preparation of N-terminal monoferrictransferrin is described.     

Isolation of fungi belonging to the genera Geotrichum and Trichosporum from human dermal lesions

Summary Isolates of Geotrichum and Trichosporum spp. obtained from patients with a variety of dermal lesions were studied. Among 2,202 cases examined, microorganisms of these genera were recovered from 100 (4,5%); there were 38 isolates of Geotrichum- and 62 of Trichosporum- spp. Most isolations were obtained from nails: 52 cases. The species most frequently found were T. beigelii (25 cases) and G. candidum (30 cases). In 50 of the patients, these fungi were isolated in pure culture, in an additional 40 Trichosporum spp. were found. Mixed cultures with C. albicans were observed in 28 patients, with other Candida spp. in 16 and with dermatophytes in 6. Among the patients whose isolations occurred in pure cultures, the number of colonies recovered was large in 20 cases, 1 with Geotrichum candidum — 19 with Trickosporum (16 T. beigelii, 3 T. capitatum). The relationship between the isolated yeast-like fungi and the dermal lesion was considered to be direct in these 20 patients.

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Sumario Se llevó a cabo un estudio sobre los géneros Geotrichum y Trichosporum aislados de lesiones cutáneas. De un total de 2.202 pacientes estudiados se hallaron 100 cuyos cultivos mostraban desarrollo de los microorganismos pertenecientes a estos géneros, encontrándose 38 casos con Geotrichum y 62 con Trichosporum. La mayoría de los aislamientos se realizaron a partir de material ungueal (52 casos). Las especies mas frecuentemente aisladas fueron T. cutaneum y G. candidum con 25 y 30 cultivos, en su orden. En 50 pacientes el aislamiento ocurrió en cultivo puro, 10 veces en el caso de Geotrichum y 40 en el de Trichosporum. Se observaron cultivos mixtos con C. albicans en 28 oportunidades, con otras especies de Candida en 16 y con dermatofitos en 6. Entre los casos con cultivos, el número de colanias rue alto en 1 paciente del cual se aisló G. candidum y en 19 de los cuales se recuperó Trichosporum (T. cutaneum 16, T. capitatum 3). Estos datos se analizan en el texto en relación con el posible papel etiológico que dichos microorganismos pudieran desempeñar en lesiones dérmicas.

     

IP3-and cAMP-induced responses in isolated olfactory receptor neurons from the channel catfish

Summary Olfactory receptor neurons enzymatically dissociated from channel catfish olfactory epithelium were depolarized transiently following dialysis of IP₃ or cAMP (added to the patch pipette) into the cytoplasm. Voltage and current responses to IP₃ were blocked by ruthenium red, a blocker of an IP₃-gated Ca²⁺-release channel in sarcoplasmic reticulum. In contrast, the responses to cAMP were not blocked by extracellularly applied ruthenium red, nor by l-cis-diltiazem or amiloride and two of its derivatives. The current elicited by cytoplasmic IP₃ in neurons under voltage clamp displayed a voltage dependence different from that of the cAMP response which showed marked outward rectification. A sustained depolarization was caused by increased cytoplasmic IP₃ or cAMP when the buffering capacity for Ca²⁺ of the pipette solution was increased, when extracellular Ca²⁺ was removed or after addition of 20–200 nm charibdotoxin to the bathing solution, indicating that the repolarization was caused by an increase in [Ca _i ] that opened Ca²⁺-activated K⁺ channels. The results suggest that different conductances modulated by either IP₃ or cAMP are involved in mediating olfactory transduction in catfish olfactory receptor neurons and that Ca²⁺-activated K⁺ channels contribute to the termination of the IP₃ and cAMP responses.Abbreviations ATP adenosine 5-triphosphate - BAPTA (bis-(o-aminophenoxy)-ethane-N-N-N-N)-tetraacetic acid - cAMP adenosine cyclic 3,5-monophosphate - cGMP guanosine cyclic 3,5-monophosphate - CTX charybdotoxin - DCB 3,4-dichlorobenzamil - EDTA ethylenediaminetetraacetic acid - EGTA ethylenglycol-bis-(b-aminoethyl)-N-N-N-N-tetraacetic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - IP₃ inositol-1,4,5-triphosphate - NMDG N-methyl-d-glucamine We would like to thank the Tanabe Seiyaku Co., Ltd., for their gift of l-cis-diltiazem. This work was supported by National Institutes of Health grants DC00566 and BRSG S07RR05825.     

Tandem duplication of proximal 5q.

A 3.5-year-old boy with a de novo tandem duplication 5q11.1----5q15 is reported. Since the physical stigmata of seven liveborn cases with 5q proximal duplications are variable and inconspicuous, a recognizable syndrome could not be delineated. On the contrary, the associated developmental delay seems to be severe in duplications extending into 5q22 and mild in duplications 5q11----q13.     

Second messenger signaling in olfactory transduction

Olfactory receptor neurons respond to odorants with G-protein mediated increases in the concentration of cyclic adenosine 3′,5′-monophosphate (cAMP) and/or inositol 1,4,5-triphosphate (InsP₃). These two second messengers directly regulate opening of cAMP- and InsP₃-regulated conductances localized to the apical transduction compartments of the cell (cilia and olfactory knob). In the presence of physiological concentrations of extracellular Ca²⁺, these second messenger regulated conductances mediate influx of Ca²⁺ into the olfactory neuron resulting in large, localized increases in intracellular Ca²⁺ ([Ca²⁺]_i). A significant advance in our understanding of the molecular mechanisms of olfaction is the recent realization that this increase in [Ca²⁺]_i plays an important role as a “third messenger” in olfactory transduction. Second messenger dependent increases in [Ca²⁺]_i cause opening of ciliary Ca²⁺-activated Cl⁻, cation and/or K⁺ channels that can carry a large percentage of the generator current, thus amplifying the signal substantially. As a result of this sequence of events, the generator potential in olfactory neurons can be depolarizing, leading to excitation of the neuron, or hyperpolarizing, leading to suppression of basal action potential firing rate. This dual effect of odorants on olfactory neurons may play an important role in quality coding and in the ability to detect low concentrations of odorants, particularly in complex mixtures. © 1996 John Wiley & Sons, Inc.     

AFLP assessment of genetic variability in cassava accessions (Manihot esculenta) resistant and susceptible to the cassava bacterial blight (CBB).

Cassava bacterial blight (CBB) is caused by Xanthomonas axonopodis pv. manihotis (Xam). Resistance is found in Manihot esculenta and, in addition, has been introgressed from a wild relative, M. glaziovii. The resistance is thought to be polygenic and additively inherited. Ninety-three varieties of M. esculenta (Crantz) were assessed by AFLPs for genetic diversity and for resistance to CBB. AFLP analysis was performed using two primer combinations and a 79.2% level of polymorphism was found. The phenogram obtained showed between 74% and 96% genetic similarity among all cassava accessions analysed. The analysis permitted the unique identification of each individual. Two Xam strains were used for resistance screening. Variation in the reaction of cassava varieties to Xam strains was observed for all plant accessions. The correlation of resistance to both strains, had a coefficient of 0.53, suggesting the independence of resistance to each strain. Multiple correspondence analysis showed a random distribution of the resistance/susceptibility response with respect to overall genetic diversity as measured by AFLP analysis. A total heterozygosity index was calculated to determine the diversity within clusters as well as among them. Our results demonstrate that resistance to CBB is broadly distributed in cassava germplasm and that AFLP analysis is an effective and efficient means of providing quantitative estimates of genetic similarities among cassava accessions.