PubMed Health⌕ Search

Biomedical subjects

J Howe

Publications and source records attributed to J Howe.

At least 37 records · Page 2Linked to original sources
PubMed1998

Ultrastructure of the nucleus of the Iodamoeba bütschlii cyst.

The ultrastructure of the Iodamoeba bütschlii cyst from human feces was studied. The glycogen mass appears as a compact dense body in the cytoplasm without any surrounding membrane. The cytoplasm has no mitochondrion. The nucleus shows a distinct nucleolus filled with electron-dense particles. On one side of the nucleolus are electron-dense cytoplasmic masses measuring 200-400 nm. The nuclear membrane is two-layered and shows pores.

Amebiasis↗
PubMed1998

Scanning electron microscopy of Blastocystis hominis cysts.

Scanning electron microscopy of Blastocystis hominis cysts reveals that some cysts have an outer coat, whereas others are naked. If intact, the outer coat forms a fan-like structure around the cyst and its surface is granular. The fragmented outer coat adheres to other cysts and bacteria, forming irregular clumps.

Animals↗
PubMed1998

Comparison of supported living and traditional residential services in the state of Oregon.

Supported living has been described as an approach that contributes to higher lifestyle quality. We compared supported living and traditional residential support. Twenty supported living participants were matched with 20 participants receiving traditional support. Results indicated that participants receiving supported living services were more likely to be experiencing features of supported living and that supported living participants experienced significantly more community activity variety, did community activities more frequently, and did preferred community activities more frequently. Further, they engaged in activities with more people and did activities with these people more frequently. The costs were similar for providing supported living and traditional support.

Adult↗
PubMed1997

Variation in the cyst morphology of Blastocystis hominis.

Two types of Blastocystis hominis cyst are passed in human feces, one with an outer fibrillar coat and the other without it. The outer fibrillar coat is shed as the cyst matures, but another fibrillar coat forms that is closely attached to the cyst wall and is clearly visible at high magnification in the electron microscope. The internal structure of the two cyst form is similar.

Animals↗
PubMed1997

Experimental Blastocystis hominis infection in laboratory mice.

Young (less than 8 weeks old) immunocompetent BALB/c mice became infected with Blastocystis hominis after inoculation of fecal cysts orally and of in vitro axenic-culture forms intracecally. This study confirmed that the fecal cyst was the form responsible for external transmission and that the mode of transmission was by the fecal-oral route. The infection was self-limiting and the infected BALB/c mice appeared normal except that some of them showed weight loss and lethargy. Both vacuolar and granular forms were found in the cecum, but only cyst forms were observed in the colon. Histological examination of the cecum and colon showed intense inflammatory-cell infiltration, edematous lamina propria, and mucosal sloughing. It is apparent that although B. hominis is not invasive, it is capable of causing pathogenesis in BALB/c mice.

Animals↗
PubMed1997

Observations on the surface coat of Blastocystis hominis.

The surface coat of Blastocystis hominis was studied in the electron microscope. In some cells the surface coat was seen in two layers; the external layer was more electron-dense and fragmented than the internal layer. It appears that the surface coat is being continuously formed by the parasite and shed in the environment. The fibrillar material of the surface coat attaches to the bacteria, in some cases, completely surrounding them, possibly causing cytoplasmic damage to the bacterial cell as indicated by loss of electron density.

Animals↗
PubMed1997

Survival of Blastocystis hominis clones after exposure to a cytotoxic monoclonal antibody.

Our previous studies have shown that monoclonal antibodies (MAbs) to Blastocystis hominis react mainly with carbohydrate epitopes, while 1 MAb (1D5) reacts specifically with a protein of 30.5 kDa. In the present study, 3 monoclonal antibodies (1D5, 1E7 and 4F7) were used in immunogold localization. 1E7 and 4F7 were found to react primarily with the surface coat, while 1D5 was plasma membrane-specific. In the presence of complement, only 1D5 exhibited a cytotoxic effect on B. hominis whereas 1E7 and 4F7 did not, suggesting that the surface coat of B. hominis could serve as an immunological barrier against host antibodies. Using a recently described agar plating method, only 1D5 exhibited significant (P < 0.01) complement-independent cytotoxicity to B. hominis, inhibiting colony growth at low concentrations. Parasites that had been exposed to 1D5 were morphologically smaller than those that were not exposed to this MAb. Colonies that grew in the presence of 1D5 were isolated and grown in liquid medium containing increasing amounts of the cytotoxic MAb. Two clones that grew well in liquid medium containing 1D5 were also able to develop into colonies in soft agar. This study has shown that the 30.5 kDa protein found on the plasma membrane of B. hominis is a functionally important protein and that not all cells within a certain population would be susceptible to the cytotoxic effects of 1D5. These findings suggest that a heterogenous population exists in continuously maintained cultures of B. hominis.

Animals↗
PubMed1997

Expression of the dengue virus structural proteins in Pichia pastoris leads to the generation of virus-like particles.

We have expressed cDNA encoding the dengue virus structural proteins in Pichia pastoris by chromosomal integration of an expression cassette containing the dengue virus structural genes (CprME). The yeast recombinant E protein migrated during SDS-PAGE as a 65 kDa protein when analysed by Western blotting and radioimmunoprecipitation, which is the expected molecular mass for correctly processed and glycosylated E protein. Treatment with endoglycosidases showed that the recombinant E protein was modified by the addition of short mannose chains. The E protein migrated with a buoyant density of 1.13 g/cm3 when analysed using sucrose density gradient centrifugation. Spherical structures with an average diameter of 30 nm, whose morphology resembles dengue virions, were observed in the purified fractions using transmission electron microscopy. Furthermore, the virus-like particles were immunogenic in animals and were able to induce neutralizing antibodies. This is the first report that expression of the structural genes of a flavivirus in yeast is able to generate particulate structures that resemble virions.

Centrifugation, Density Gradient↗
PubMed1996

Chlamydia trachomatis: symptoms and consequences.

In the second of two articles on sexually transmitted diseases, the author discusses chlamydia trachomatis. The article reviews the symptoms and consequences of chlamydia infection, and recommends an education strategy to increase public and professional awareness of the condition.

Anti-Bacterial Agents↗
PubMed1996

A new sodium channel alpha-subunit gene (Scn9a) from Schwann cells maps to the Scn1a, Scn2a, Scn3a cluster of mouse chromosome 2.

We have used a total of 27 AXB/BXA recombinant inbred mouse strains to determine the chromosomal location of a newly identified gene encoding an alpha-subunit isoform of the sodium channel from Schwann cells, Scn9a. Linkage analysis established that Scn9a mapped to the proximal segment of mouse chromosome 2. The segregation of restriction fragment length polymorphisms in 145 progeny from a Mus spretus x C57BL/6J backcross indicates that Scn9a is very tightly linked to Scn1a (gene encoding the type I sodium channel alpha-subunit of the brain) and forms part of a cluster of four Scna genes located on mouse chromosome 2.

Animals↗
PubMed1996

Colony formation of Blastocystis hominis in soft agar.

This is the first description of a method for growing axenized Blastocystis hominis as colonies in petri dishes containing soft agar. Blastocystis cells cultured in two types of agar appeared to show different colonial morphologies as well as differing colony yields. Microscopic examination of the colonies revealed many amoeboid and giant cells. Many cells were also shown to possess thin filament-like structures that appeared to stretch across the central vacuole.

Agar↗
PubMed1996

Observations on the ultrastructure and viability of the cystic stage of Blastocystis hominis from human feces.

This report describes the ultrastructure and viability of cysts of Blastocystis hominis from feces of infected patients. The cysts were round to ovoid, measured 2-5 microns in size, and contained a condensed cytoplasm that had vacuoles of varying sizes, four nuclei, and as many as six cristate mitochondria. The cell wall was rather electron-lucent. Surprisingly, chromatoid-like structures were found in the cytoplasm and nucleus of some of the cysts. These have not previously been reported in Blastocystis. The cysts can survive in water for up to 19 days at normal temperatures but are fragile at extreme temperatures and in common disinfectants.

Animals↗
PubMed1996

The effect of papermill wastewater and organic amendments of sodium accumulation by potted cottonwoods.

In this experiment, the impacts of pulp mill effluent irrigation, Fraser cottonwood (Populus deltoides 'Fraser') seedlings, and pulp sludge and manure soil amendments on sodium accumulation and distribution in the soil profile were evaluated during a 6 month greenhouse study. Sludge soil amendments and wastewater irrigation did not reduce stem biomass production of the cottonwood. Increased stem biomass production associated with manure soil amendments resulted in greater total uptake of sodium into stem material. This uptake was 0.002% of wastewater sodium inputs. In containers with seedlings, sodium concentrations were less in the surface horizon and more in the lower horizons than in containers with no seedlings. Infiltration rates and total sodium accumulation in the soil profile were not affected by the presence of Fraser cottonwood or the application of sludge or manure amendments to soil.

Journal Article↗
PubMed1995

Ultrastructure of Blastocystis hominis cysts.

Blastocystis hominis cysts were concentrated from human faeces by repeated washing in distilled water and centrifugation on Ficoll-Paque. This procedure gave a concentrated suspension of cysts without yielding any non-cystic forms. The cysts were examined by both transmission (TEM) and scanning electron microscopy (SEM). Cysts were surrounded by a fibrillar layer that appeared porous in SEM. Many naked cysts without the fibrillar layer were also visible in SEM. They were variable in shape but mostly circular to oval. The diameter of the cyst without the fibrillar layer was 3.5 microns in both TEM and SEM. The nuclear structure was typical of Blastocystis and exhibited multiple mitochondria with poorly developed cristae. Glycogen was present in small to large clumps in the cytoplasm. The cyst wall was 5-100 nm thick and was bounded internally by an electron-dense plasmalemma.

Animals↗
PubMed1995

Tubulovesicular elements in Blastocystis hominis from the caecum of experimentally-infected rats.

By transmission electron microscopy (TEM), tubulovesicular elements were seen in Blastocystis hominis obtained from the caecum of experimentally-infected rats. These appeared to arise from the peripheral cytoplasm and were rounded, oval or elongate in sections. It is suggested that these elements form a network for transfer of nutrients to the periphery during the process of encystation.

Animals↗
PubMed1995

Peripheral blood flow in the elderly during inhalational anaesthesia.

We investigated whether aging altered the peripheral vascular effects of inhaled anaesthetic agents. Forearm blood flow (FBF) was measured in 20 young (18-34 yrs) and 21 healthy elderly (60-79) patients receiving isoflurane or halothane with 66% nitrous oxide (N2O) in oxygen (O2). After etomidate 0.3 mg/kg and vecuronium 0.1 mg/kg, the trachea was intubated and controlled ventilation instituted with 66% N2O in O2. Halothane or isoflurane were administered to achieve end-tidal concentrations of 0.5% halothane or 0.9% isoflurane after 20 min. FBF was measured by venous occlusion plethysmography during the 20 min study period. Induction of anaesthesia with etomidate decreased FBF below baseline (awake) values in both elderly and young; intubation returned FBF to baseline values in the young but not in the elderly. FBF decreased below baseline values in young and elderly patients receiving halothane and in elderly patients receiving isoflurane but not in young patients receiving isoflurane. FBF was significantly greater in young patients receiving isoflurane than halothane after 20 min administration. We conclude that perfusion of forearm muscle and skin is maintained in the young but not in the elderly during anaesthesia with isoflurane/N2O. Perfusion of forearm muscle and skin decreases in both young and elderly patients during anaesthesia with halothane/N2O. The cardiovascular effects of isoflurane/N2O and halothane/N2O did not differ significantly in healthy elderly patients.

Adolescent↗