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Biomedical subjects

J I Phillips

Publications and source records attributed to J I Phillips.

At least 19 recordsLinked to original sources
PubMed2007

Rock drills used in South African mines: a comparative study of noise and vibration levels.

OBJECTIVES: To compare the noise and vibration levels associated with three hand-held rock drills (pneumatic, hydraulic and electric) currently used in South African mines, and a prototype acoustically shielded self-propelled rock drill. METHODS: Equivalent A-weighted sound pressure levels were recorded on a geometrical grid, using Rion NL-11 and NL-14 sound level meters. Vibration measurements were conducted on the pneumatic, hydraulic and electric drills in accordance with the ISO5349-1 (2001) international standard on human exposure to hand-transmitted vibration, using a Brupsilonel and Kjaer UA0894 hand adaptor. PCB Piezo accelerometers were used to measure vibration in three orthogonal directions. No vibration measurements were conducted on the self-propelled drill. RESULTS: All four drills emitted noise exceeding 85 dB(A). The pneumatic drill reached levels of up to 114 dB(A), while the shielded self-propelled drill almost complied with the 85 dB(A) 8 h exposure limit. Vibration levels of up to 31 m s(-2) were recorded. These levels greatly exceed recommended and legislated levels. CONCLUSIONS: Significant engineering advances will need to be made in the manufacture of rock drills to impact on noise induced hearing loss and hand arm vibration syndrome. Isolating the operator from the drill, as for the self-propelled drill, addresses the problems of both vibration and noise exposure, and is a possible direction for future development.

Humans↗
PubMed2001

Asbestos lung fibre concentrations in South African chrysotile mine workers.

Mesothelioma has not been found in South African chrysotile miners and millers despite decades of producing about 100000 tons of the mineral per year. One possible explanation for the scarcity or absence of the cancer may be a relative lack of contaminating fibrous tremolite, an amphibole that variably occurs with chrysotile ores. The fibre content in the lungs of nine former chrysotile mine workers was ascertained by transmission electron microscopy. Despite fairly long service in most cases (median 9.5 yr; range 32-4 yr) the concentrations of chrysotile fibres were relatively low: only two cases exceeded 1.14 million fibres/g dried lung. Tremolite fibre levels were even lower: less than 1 million fibres/g dried lung in all but one case. Tremolite fibre concentrations exceeded those of chrysotile in only two cases. These results support the contention that South African chrysotile is not heavily contaminated by tremolite.

Adult↗
PubMed2000

The pulvillus and empodium in Culex quinquefasciatus: visualization with the light microscope and a study of fine structure with the scanning electron microscope.

The empodia and pulvilli on each postarsus were examined in male and female Culex quinquefasciatus. Up to 160x magnification was required to see them clearly under the stereo light microscope but they were more readily visible under the compound light microscope as slide mounts at 100-200x magnification. Scanning electron micrographs of female and male pulvilli showed that they are either well developed (females) or inconspicuous (males) and that they consist of setal tufts composed of both pointed and trumpet-ended setae. The ultrastructure of the pulvilli is described and their possible function in oviposition is discussed.

Animals↗
PubMed1998

Chlamydia pneumoniae in atheroma: consideration of criteria for causality.

AIMS: (1) To seek evidence of the existence of Chlamydia pneumoniae in a spectrum of atheromatous lesions in different types of arteries from individuals of different ages, using a polymerase chain reaction (PCR) assay supported by electron microscopy and immunocytochemistry; (2) to use electron microscopy to examine interactions between C pneumoniae and the cells present in the arterial tissue; (3) to assess the extent to which the data fulfil the criteria for causality. METHODS: At necropsy examination, 35 arterial specimens were taken from 25 subjects. The grade of atheroma was determined macroscopically and microscopically and the tissues coded and examined by the three techniques. RESULTS: Of the 35 specimens, 24 had macroscopic or microscopic atheromatous lesions of varying degree. Twenty two of the 35 specimens were examined by electron microscopy, C pneumoniae-like bodies being found in 11 (50%); seven specimens were examined by the immunocytochemical method, positive staining being detected in three; and all specimens were examined by the PCR technique, 15 (43%) being PCR positive. Overall, of the 24 specimens with lesions, 17 (71%) were positive by at least one of the three tests, whereas of the 11 specimens without lesions, only one was positive. The positive specimens comprised 10 of 19 aortas, three of six iliac arteries, and one coronary and one pulmonary artery. C pneumoniae was detected in four of six specimens in which there were early changes and in a 20 year old subject. Concerning the 25 subjects, of 17 who had atheromatous arteries, 14 (82%) were C pneumoniae positive and of the eight who had normal arteries, none was positive. CONCLUSIONS: There is a strong correlation between C pneumoniae and arterial atheromatous lesions. The organism may contribute to the disease process by damaging smooth muscle cells.

Adult↗
PubMed1994

Death following exposure to fine particulate nickel from a metal arc process.

A man was taken ill suddenly while spraying nickel using a thermal arc process. He was relieved of his duties and sent home. His condition deteriorated and he was admitted to hospital with a diagnosis of pneumonia. Thirteen days after exposure he died. At post mortem examination the cause of death was determined to be shock lung or Adult Respiratory Distress Syndrome (ARDS). Reproduction of the conditions under which the man had operated the metal arc process produced nickel concentrations of 382.1 mg m-3 in the air next to the operator. Of this nickel, 64.6% was in the form of particles less than 1.4 microns in diameter; the majority being 50 nm in diameter. The total amount of nickel inhaled by the man, who operated the process for 90 min, was estimated to be nearly 1 g. The toxicity of the nickel is thought to be associated with the very fine particulate nature of the metal fume and the large amount inhaled. The importance of wearing adequate protective equipment while operating this metal arc process is stressed.

Adult↗
PubMed1990

Demyelinisation in the spinal cord of vitamin B12 deficient fruit bats.

1. Vitamin B12 deficiency induced in the fruit bat by a combination of dietary deprivation and exposure to nitrous oxide (N2O) is accompanied by profound neurological impairment, thus providing an experimental model for the study of vitamin B12 neuropathy. 2. Electron microscopy of the spinal cord of vitamin B12 deficient bats shows marked changes in the myelin of the posterior columns in the form of distension, separation and vacuolation of myelin lamellae similar to the changes described in the dietary induced B12 deficient monkey model. 3. No equivalent change occurred in bats exposed to N2O and supplemented with vitamin B12.

Animals↗
PubMed1990

Red or rufous albinism in southern Africa.

Red or rufous albinism is a rare type of oculocutaneous albinism described, but not as yet fully investigated, in Africa and New Guinea. Twelve rufous albino subjects from 10 families participated in this preliminary study. The prevalence of rufous albinism was found to be approximately one in 8,580 among school children in the negroid population. The combination of the unusual red skin colour, ginger to reddish hair colour, low susceptibility to sun damage, and minimal visual problems, in affected individuals, suggested that they form a group which is distinct from the brown and other types of albinism. The mode of inheritance was found to be recessive. Tyrosinase assays showed that rufous albinos are tyrosinase positive and on electron microscopy studies normal melanosomes and melanocytes were observed in hair bulbs and skin. Visual evoked potential testing did not show the gross decussation abnormalities of the optic pathway detected in other types of albinism. Rufous albinism might be at one end of the spectrum of types of oculocutaneous albinism and, because affected people have such mild symptoms, their inclusion in this group might be debatable.

Adolescent↗
PubMed1989

Lack of cilia and squamous metaplasia in upper respiratory tract biopsies from children.

Biopsies were obtained from 47 children with upper respiratory tract infection aged 30 days - 12 years. All had been extensively investigated and no underlying cause for their symptoms could be found. A total of 63 specimens (46 from the inferior nasal turbinate, 8 from the trachea and 9 from the carina or bronchus) were examined. Only 4 showed no degree of squamous metaplasia and 8 showed significant numbers of acquired-type morphological abnormalities of the cilia. Twenty-six of the 63 biopsies had significantly reduced numbers of cilia and 34 had no cilia. Inherited-type changes were seen in only 1 patient. The net result of a lack of cilia and the immotile-cilia syndrome is the same--absence of mucociliary transport.

Biopsy↗
PubMed1989

Neuroblastoma in adults. A report of 3 cases.

Well documented as one of the more frequent tumours of childhood, neuroblastomas in adults are rare. Correct diagnosis, and distinction from other small-cell neoplasms, is thus often delayed. Three further cases are described in 2 women and 1 man between the ages of 26 years and 47 years. Metastatic disease existed at the time of initial presentation in 1 patient, while another had experienced multiple recurrences at the primary site before correct diagnosis. All, however, had a favourable response to chemotherapy, albeit in the short term. Primary diagnosis was made by fine-needle aspiration cytology, together with electron microscopic evaluation of aspirated cells in 1 case. The histological, cytological and electron microscopic characteristics of neuroblastomas are presented and illustrated, and their differentiation from other small cell tumours in adults discussed.

Adult↗
PubMed1989

The fate of intravenously injected tissue ferritin in pregnant guinea-pigs.

The organ distribution of intravenously injected hepatic ferritin either labelled with 59Fe or with 59Fe and 125I, was studied in pregnant guinea-pigs. At 5 h 71.2% of injected 59Fe was present in the placenta and fetus. Transfer of 59Fe to the fetus was slow, with 11.2% present at 5 h and 38.6% at 21 h. Analysis of a placental cellular lysate for 59Fe and 125I revealed that the injected iron was present as intact ferritin at 2 h but by 21 h the ferritin had been catabolized, the 125I excreted and the 59Fe incorporated into endogenous ferritin. Most of the fetal 59Fe counts were detected in the liver, with 35.3% of the transferred 59Fe in ferritin, 30.4% in haemoglobin and 10.6% in a low molecular weight pool. The uptake of labelled ferritin by the placenta was inhibited by a 300-fold molar excess of unlabelled ferritin but not by albumin, asialofetuin or by the injection of carbon particles. A nonsignificant reduction in uptake was noted after injection of mannosylated bovine serum albumin. The mannosidase inhibitor swainsonine had no effect. Iron transfer to the fetus was not affected by various microtubular inhibitors. Presaturation of endogenous transferrin with oral carbonyl iron prevented iron release from the feto-placental unit back into the maternal circulation. In consequence, marrow 59Fe uptake by the maternal marrow was reduced. The ferrous chelator 2,2'-bipyridine significantly reduced 59Fe transfer to the fetus and this occurred irrespective of whether the chelator was given prior to or after 59Fe ferritin administration. The ferric chelator desferrioxamine had no such effect. Electron microscopy of placental tissues revealed endocytosis of ferritin molecules. These results indicate that the guinea-pig placenta takes up homologous tissue ferritin and transfers the iron slowly to the fetus after reductive mobilization. The process is compatible with a receptor-mediated pathway.

Animals↗
PubMed1989

Invasive potential of noncytotoxic enteropathogenic Escherichia coli in an in vitro Henle 407 cell model.

The invasive capacity of 13 enteropathogenic Escherichia coli strains was assessed in vitro in Henle 407 cell culture. Both fluorescent microscopy of infected monolayers stained with acridine orange and electron microscopy revealed the presence of intracellular bacteria. As shown by acridine orange-stained infected monolayers, the number of internalized bacteria increased with time. Monolayers infected for 3 h were treated with antibiotics and either [14C]glutamine or [3H]leucine and incubated for various time intervals, after which the amount of radioactivity present in the washed monolayers was measured. A significant (P less than 0.005) increase in uptake was evident for up to 4 h after the addition of radiolabeled amino acid. This finding was confirmed by an increase in bacterial number in cultured cells and in protein concentration of infected cells with time. None of the South African enteropathogenic E. coli isolates used in these studies produced Vero cytotoxin. These findings demonstrate that, in addition to adherence, cell penetration and intracellular multiplication take place in epithelial cell-derived tissue culture cells infected by enteropathogenic E. coli.

Amino Acids↗
PubMed1988

Oestrogen receptor assay by ER-D5 immunocytochemistry fails to correlate with ligand-binding assay in breast cancer.

Results obtained with a conventional reference ligand-binding assay were compared with those from an immunocytochemical method employing ER-D5 antigen, a supposedly oestrogen-receptor-related protein. In a group of 144 histologically proven breast carcinomas, no direct correlation could be established. Only 52% of cases would have corresponded in diagnosis. The incidence of false-negatives by ER-D5 immunocytochemistry is of the order of 70% while 32% of patients were false-positive by this method. Since both methods are employed to predict therapeutic responses to hormonal manipulation, the discrepancy between the methods is alarming. While the prognostic and predictive index of conventional oestrogen-receptor assays is well documented, correlation of these assays with ER-D5 immunocytochemistry has not been demonstrated. On the basis of these results, and pending further investigation, the replacement of conventional oestrogen-receptor methods by immunocytochemistry using this antibody is not recommended.

Antibodies, Monoclonal↗
PubMed1987

Kaposi's sarcoma in different populations in South Africa.

Patients with Kaposi's sarcoma (13 black and 5 white heterosexuals and 2 homosexuals with the acquired immunodeficiency syndrome (AIDS)) were investigated clinically, histologically, serologically and immunologically. Clinically, lymph node involvement was present in 9 of the 13 black heterosexuals, but was not seen in the other two groups. Oedema, which was seen in 13 of the 14 black patients, was only present in 1 white patient. The lesions were of the nodular cutaneous type except in the AIDS patients who presented with plaque-like lesions. Whereas all non-AIDS patients were negative for HTLV-III antibodies, both AIDS patients were positive and showed a marked cell-mediated immune (CMI) deficiency. Only 1 heterosexual white and 4 heterosexual black patients had some degree of CMI deficiency. South Africans with Kaposi's sarcoma do not have significant underlying immunodeficiency or associated opportunistic infections. No serological or electron microscopic evidence was found to support the aetiological role of cytomegalovirus in Kaposi's sarcoma. The findings suggest that the cell of origin of this tumour is the vascular endothelial cell.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Squamous cell carcinoma with anemone cell features.

A tumor from a 52-year-old Albino male had the ultrastructural features of an anemone cell tumor. Evidence of squamous differentiation was seen by electron microscopy and immunohistochemistry. "Anemone cell" tumors have been shown to be classifiable as either carcinomas or lymphomas; the term therefore does not describe a discrete entity or constitute a definitive diagnosis. Treatment with radiotherapy was successful in this case, while chemotherapy appeared to have little effect.

Carcinoma, Squamous Cell↗
PubMed1986

Ochronosis in black South Africans who used skin lighteners.

Skin-lightening preparations containing hydroquinone are used extensively by black South Africans. In some instances these preparations produce severe and irreversible cutaneous damage. Clinically, the deleterious effects begin with darkening and coarsening of the skin, followed by a hyperpigmented papular condition. Histologically, there is increased basophilia of the collagen, followed by the formation of yellow fibers. These yellow fibers swell and break down to form an amorphous eosinophilic material. Electron microscopy shows that the changes arise from a breakdown of normal collagen.

Humans↗