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Biomedical subjects

R F Carter

Publications and source records attributed to R F Carter.

At least 55 records · Page 3Linked to original sources
PubMed1983

Site of expression of immunity to Naegleria fowleri in immunized mice.

An experiment was performed which confirmed a previous finding that mice are protected against Naegleria fowleri infection by immunization with amoeba-free supernatant from amoeba cultures. Histological observations suggested that this protection is expressed mainly at the nasal mucosa and possibly results from the combined effects of polymorphonuclear leucocyte-mediated killing of the amoeba and mechanical elimination of the organisms by extensive shedding of necrotic epithelium.

Amebiasis↗
PubMed1983

Cytogenetic studies: an essential part of the paediatric necropsy.

Chromosome studies were attempted on 97% of necropsies carried out in the Department of Histopathology of the Adelaide Children's Hospital over the four-year period ending May 1981. Results were obtained from 89% of necropsies of which 7.5% had major chromosome abnormalities. The chromosome results are analysed according to the category of the necropsy and to primary cause of death. It is recommended that cytogenetic studies be performed on all stillbirths and infants dying at less than 28 days of age except in cases of isolated CNS malformation, sudden infant death syndrome (SIDS), trauma, or known single gene defects.

Abortion, Spontaneous↗
PubMed1982

Malignant carcinoid tumors in children.

The clinical, light microscopic, and ultrastructural features of four malignant carcinoid tumors in children, three boys and one girl ages 8--14 years, are described. Extensive metastases to multiple organs were present in three, and in the fourth child there was diffuse local infiltration of the bowel wall, which resembled a lymphoma. The primary tumor arose in the ileum in one child and in the transverse colon in another. In two children, the primary sites could not be determined; one patient is still alive and in the other, permission for autopsy was refused. Electron microscopy showed moderate numbers of neurosecretory granules in some cells in all cases. One patient with extensive metastases showed repeated partial response to radiotherapy and chemotherapy. Eight benign appendiceal carcinoids were seen at the same hospital over the same period, suggesting malignant carcinoids may be more common in children than often assumed.

Adolescent↗
PubMed1982

The effects of varying current levels of electrical stimulation.

An effort has been made to find an experimental delayed union of a long bone that could be used to evaluate the osteogenic effect of different current strengths. It is important that the optimum current strength be determined. Any such model should be able to produce a difference in new bone formation with an active and an inactive stimulator, particularly one using a 20 microA direct current. Attempts to produce a nonunion model in dogs were unsatisfactory, possibly because the defect was too small and surrounded by normal bone, and excessive movement occurred at the cathode plate. The optimum range of electrical stimulation using a titanium cathode has not been established by this work. The changes in serum alkaline phosphatase, serum calcium and serum phosphorus concentrations in response to trauma have been shown to be the same in the bone formation induced by electrical current.

Animals↗
PubMed1981

A fatal case of meningoencephalitis due to a free-living amoeba of uncertain identity--probably acanthamoeba sp.

There are 2 main types of meningoencephalitis caused by free-living amoebae. The first is a well-defined acutely fatal disease resembling fulminating bacterial meningitis. It is caused by the single species Naegleria fowleri. The second is a more poorly defined disease that runs a subacute or chronic course and is characterized by focal granulomatous lesions in the brain. The causative organisms are probably Acanthamoeba sp. in most cases, but it is possible that other genera may be involved. The first case of the subacute form of the disease to be recognized in Australia is described. A 2 1/2-yr-old, previously well girl presented with ataxia and lower motor neurone paralyses. The cerebrospinal fluid was pleocytic and she was thought to be suffering from a relatively minor viral brain-stem encephalitis. Her symptoms persisted in a peculiarly fluctuating way for 30 d when she suddenly collapsed and died from an intracranial haemorrhage. Necropsy showed focal granulomatous lesions associated with necrotizing vasculitis in the basal regions of the brain. The lesions contained well preserved free-living amoebae which were morphologically different from N. fowleri and most closely resembled Acanthamoeba sp. The ultrastructure of the organisms was particularly well preserved and is described in some detail. Immunohistological studies also excluded N. fowleri but were inconclusive for Acanthamoeba or other genera of free-living amoebae. Difficulties with the diagnosis and treatment of this disease are discussed and some practical suggestions are made.

Amoeba↗
PubMed1979

Down's syndrome in South Australia.

In a survey of Down's syndrome in South Australia, 921 persons, both living and deceased, were identified; 717 individuals with the disorder were living in South Australia. Cytogenetic confirmation of the diagnosis had been made in 774 cases. From 1955 to 1977, the over-all incidence of Down's syndrome at birth was found to be 1.175/1000 live births. The incidence of Down's syndrome was significantly lower over the last five years of this period than for the first 18 years; thus it appears that the incidence of Down's syndrome in South Australia is falling. Analysis of maternal age changes with time has not revealed any changes to the maternal age-specific rates for Down's syndrome, although the rate for mothers aged 25 years or younger appears to be falling. The proportion of Down's syndrome babies born to women aged 35 years or more has decreased from 65.7% for those born before 1950 to 30.4% for those born from 1975 to 1977; similarly, the median maternal age has fallen from 37.12 years to 28.25 years. Regression analyses of maternal age rates for Down's syndrome by single years have produced figures suitable for genetic counselling. A plea is made that Down's syndrome should become a notifiable condition.

Australia↗
PubMed1979

Electron microscopy of skin and peripheral blood lymphocytes in infantile (Santavuori) neuronal ceroid lipofuscinosis.

Skin punch biopsies and peripheral blood lymphocyte preparations from two siblings with early infantile (Santavuori) neuronal ceroid lipofuscinosis have been examined by electron microscopy. In both cases characteristic osmiophilic inclusion bodies were found in various cells in the skin and in lymphocytes. In one case, lymphocyte inclusions were detected before the onset of any symptoms as a result of a family study. This indicates the possibility of screening lymphocytes of siblings of affected patients as a result of a family study. This indicates the possibility of screening lymphocytes of siblings of affected patients with a view to early detection of the disorder.

Ceroid↗
PubMed1978

Chromosome studies at the paediatric necropsy.

The results of chromosome studies from 1193 consecutive paediatric necropsies in Edinburgh and 331 in Adelaide are given. In the Edinburgh series 51 major chromosome abnormalities were detected in 780 (6.5%) necropsies where chromosome studies were successful and in Adelaide 16 in 295 (5.4%) were found. It is suggested that chromosome studies should become an integral part of the paediatric necropsy except for deaths due to primary central nervous system lesions and trauma.

Australia↗
PubMed1978

Inhibition of VIP-stimulated intestinal secretion and cyclic AMP production by somatostatin in the rat.

The effect of somatostatin on colonic secretion induced by 10(-8) M vasoactive intestinal peptide (VIP), 10(-2) M theophylline, and 2 X 10(-3) M dibutyryl cyclic AMP was studied in muscle-stripped everted open rat colon sacs. The secretory response to VIP, measured as the decrease in net absorptive flow rate (microliters 30 min-1 mg-1 of dry weight), was maximal and equalled the responses to theophylline or dibutyryl cyclic AMP. Somatostatin (10(-5) M) blocked completely the secretory response to VIP but only partially the secretory response to theophylline or dibutyryl cyclic AMP. This difference in the extent of inhibition suggested that somatostatin exerted an inhibitory effect both before and after the point of generation of intracellular cyclic AMP. In order to test the hypothesis that one component of the action of somatostatin involved inhibition of the production of cyclic AMP, measurements of this nucleotide were made in isolated rat colon cells. Control levels of cyclic AMP measured by radioimmunoassay (12.6 +/- 1.6 pmoles per 10(6) cells) were not affected by 10(-5) M somatostatin. VIP (5 X 10(-8) M) increased cyclic AMP levels 2-fold (P less than 0.01) and this increase was blocked by somatostatin. The results indicated that somatostatin inhibits colonic secretion by exerting effects at two sites: one site lies at, and another beyond, the point of generation of intracellular cyclic AMP.

Adenylyl Cyclase Inhibitors↗
PubMed1978

46,XX/46,XX,r (2)(p25q37) mosaicism: clinical and cytogenetic studies.

A severely mentally retarded and physically handicapped girl is described who has 46,XX/46,XX,r(2)(p25q37) mosaicism. This is the first ring 2 chromosome to be described in Man. Studies of the behaviour of the ring showed that it was stable in diploid cells which had increased in frequency over a period of seven years, but unstable in tetraploid cells which were at a much higher frequency than in normal individuals. It is concluded that in some cases the phenotypic consequences of ring chromosome formation may be due more to their disturbing the regulation of cell division than to the loss of genetic material. Current models of ring chromosome behaviour do not account for the induction of tetraploidy.

Cell Division↗
PubMed1977

Electrical bone-growth stimulation in an experimental model of delayed union.

An experimental model has been devised for the consistent production of delayed bone healing of the tibia in adult dogs. A double-blind trial, with bias eliminated, was used to evaluate the use of a commercially available direct-current bone-growth stimulator with this model. The stimulator produced a statistically significant acceleration of bone healing at four weeks in the experimental model. Osteogenesis was normal, and no dysplastic, inflammatory, or neoplastic changes were found. This research has shown that electrical stimulation of bone is safe and augments bone formation. The bone-growth stimulator unit remains on trial, but in future it may alter the management of many difficult orthopaedic problems.

Animals↗
PubMed1977

Experimental delayed union of the dog tibia and its use in assessing the effect of an electrical bone growth stimulator.

A technique has been described for the consistent production of delayed bone healing of the tibia in an animal model. A controlled double blind trial, where independent observors did not know the coding of the stimulators and did not collaborate with each other, has evaluated the use of a direct current bone growth stimulator in such an animal model. The conclusion of the experiment is that this commercially available direct current stimulator does produce a significant acceleration of bone healing at 4 weeks in the experimental model used. There is no evidence of inflammatory or neoplastic changes. The eventual clinical role of electrical bone stimulation remains uncertain and many questions remain unanswered, but are promising enough to encourage a controlled clinical trial in situations of disturbed bone healing. Electrical stimulation is apparently safe and appears to significantly augment bone formation. A controlled clinical trial is now being carried out in major medical centers in Australia.

Animals↗
PubMed1976

Cytogenetic survey of a hospital for the mentally retarded.

A cytogenetic survey of all 588 patients in Strathmont Training Centre, an Australian hospital for the mentally retarded, was carried out. Abnormal karyotypes were found in 90 (15.3%) patients, of whom 73 (12.4%) had clinical Down syndrome, 12 (2.04%) other autosomal abnormalities, and 5 (0.85%) sex chromosome abnormalities.

Adolescent↗
PubMed1976

Partial and complete trisomy 9: delineation of a trisomy 9 syndrome.

Two infants with trisomy involving chromosome 9 are described. One had complete trisomy 9 and the other karyotype 47,XX,+der(9),t(7;9) (p22;q32)mat. A trisomy 9 syndrome is delineated, consisting of features of the trisomy 9p syndrome and various other malformations. These include abnormalities of the cardiovascular and urogenital systems, cranial suture anomalies, dislocation of the hips and knees and early death. A possible relationship of some of these findings to regions of 9q involved in cases of partial trisomy 9 is suggested.

Abnormalities, Multiple↗