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J C Rodger

Publications and source records attributed to J C Rodger.

At least 73 records · Page 4Linked to original sources
PubMed1985

The in vitro immunoregulatory properties of cultured murine trophoblast are not unique to this tissue.

Primary cultures of murine trophoblast (ectoplacental cone and mid-term placenta) and their supernatants were found to inhibit in vitro lymphocyte proliferative responses to concanavalin A (77-87%) and allo-antigen (52-84%). However, cultures and cell-conditioned media from non-trophoblastic tissues (embryonic sac, adult lung and liver, and B16 melanoma line) produced similar results. In all cases, the inhibitory effects were not due to reduced cell viability. Addition of anti-progesterone serum to the ectoplacental cone-lymphocyte co-cultures, at a concentration known to bind the available trophoblast-derived progesterone, did not overcome the observed suppression. The results clearly demonstrate that a range of cultured cell types, and their conditioned media, will suppress immune responses in vitro. We conclude that cultured trophoblast is not an appropriate model for studies of placental immunoregulation.

Animals↗
PubMed1984

Why so many mammalian spermatozoa--a clue from marsupials?

Mammals generally ejaculate many more spermatozoa than seem to be needed for fertilization. This apparent profligacy has not been explained, but observations made in marsupials may shed light on it. The Virginia opossum, Didelphis virginiana, inseminates only about three million spermatozoa, a very low number. As a corollary, relatively few (ca. 13 X 10(6] are stored in each cauda epididymidis. However, some 5% of the spermatozoa that the opossum ejaculates populate the oviduct about 12 h later when ovulation can be anticipated--a success rate in the female orders of magnitude greater than in eutherian mammals. It is not certain what determines the unusually efficient transport to and the high survival rate of spermatozoa in the oviduct of Didelphis, but two unusual features suggest themselves as possible contributors. Didelphis (and all other American marsupial) spermatozoa undergo a head-to-head pairing in the epididymis by the acrosomal face; this serves to isolate the acrosome of ejaculated spermatozoa from the female milieu until the pairs separate in the oviduct. Secondly, spermatozoa are housed in special crypts in the isthmus of the oviduct. Australian marsupials, which usually lack such features, store spermatozoa in the epididymis in numbers more close to those in comparably sized eutheriam mammals. Exceptions which store very low sperm numbers there can be seen in one Australian Family, the Dasyuridae . The spermatozoa of dasyurids are not paired, but the species examined possess distinctive sperm storage crypts in the oviducal isthmus similar to those in the opossum. The present findings suggest that where mechanisms exist that could protect the acrosome and, or, the whole spermatozoon in the female tract, a much lower level of sperm production can be maintained without compromising fertility. While the number ejaculated typically by any one species is probably determined ultimately by several interacting factors, it therefore seems likely that a most important one in this respect relates to conditions spermatozoa face in the female tract.

Animals↗
PubMed1984

Effect of cold stimulation on myocardial perfusion. An investigation using thallium-201 scintigraphy.

Thallium-201 scintigraphy was used to investigate the effects of cold stimulation on myocardial perfusion in 12 patients with documented coronary artery disease (group 1), nine with chest pain but without evidence of structural coronary artery disease (group 2), and 10 normal volunteers (group 3). The scintigrams were assessed both visually and numerically using a circumferential profile technique. Transient perfusion defects were identified by both techniques in six subjects in group 1, three in group 2, and two in group 3. The haemodynamic responses (assessed by the double product) of subjects with or without transient perfusion defects were not significantly different. Thus cold stimulation can provoke abnormalities of myocardial perfusion not only in patients with coronary heart disease but also in those with structurally normal coronary arteries and in some normal subjects. These results may reflect a spectrum of coronary vasomotor responsiveness to cold stimulation in both normal and ischaemic populations, and it is concluded that cold pressor techniques cannot be relied on to differentiate patients with coronary heart disease from those with atypical chest pain syndromes or even from normal subjects.

Blood Pressure↗
PubMed1983

The effects of cardioselective and non-selective beta-adrenoceptor blockade on the hypokalaemic and cardiovascular responses to adrenomedullary hormones in man.

Adrenaline was infused intravenously in nine normal volunteers to plasma concentrations similar to those found after myocardial infarction. This study was undertaken on three occasions after 5 days' treatment with placebo or the beta-adrenoceptor antagonists, atenolol or timolol. Adrenaline increased the systolic pressure by 11 mmHg, decreased the diastolic pressure by 14 mmHg, and increased the heart rate by 7 beats/min. These changes were prevented by atenolol. However, after timolol the diastolic pressure rose (+19 mmHg) and heart rate fell (-8 beats/min). Adrenaline caused the corrected QT interval (QTc) to lengthen (0.36 +/- 0.02 s to 0.41 +/- 0.06 s). No significant changes were found in the QTc when subjects were pretreated with atenolol or timolol. The serum potassium fell from 4.06 to 3.22 mmol/l after adrenaline. Serum potassium fell to a lesser extent to 3.67 mmol/l after atenolol and actually increased to 4.25 mmol/l after timolol. Adrenaline-mediated hypokalaemia appears to result from the stimulation of a beta 2-adrenoceptor linked to membrane Na+/K+-ATPase causing potassium influx.

Adult↗
PubMed1983

Effect of intravenous adrenaline on electrocardiogram, blood pressure, and serum potassium.

Increased catecholamines after myocardial infarction may contribute to the development of arrhythmias. We have infused adrenaline intravenously in nine normal volunteers to levels similar to those seen after myocardial infarction. Adrenaline caused an increase in systolic blood pressure, a decrease in diastolic blood pressure, and an increase in heart rate. Adrenaline also produced a decrease in T wave amplitude and an increase in the QTc interval. The serum potassium fell dramatically during the adrenaline infusion from a control value of 4.06 mmol/l to 3.22 mmol/l. Hypokalaemia after myocardial infarction is associated with an increased incidence of ventricular arrhythmias. Thus, circulating adrenaline may increase the frequency of arrhythmias both directly via changes in ventricular repolarisation and indirectly via adrenaline induced hypokalaemia.

Adult↗
PubMed1983

Coxsackie B infection in a general medical unit.

From January 1979 until December 1980, neutralizing antibody titres to Coxsackie B1-6 viruses were measured in sera from 220 patients presenting to a general medical unit, the majority of whom had chest pain. No four-fold or greater rises in antibody titre were detected in these hospital patients. However, 49 per cent had titres of greater than or equal to 256 to one or more Coxsackie B virus types compared with 10 per cent of the 950 persons studied during a 'normal population' survey in the West of Scotland. When a more rigorous threshold was adopted, titres greater than or equal to 512 were found in 33 per cent and 4 per cent respectively. We conclude that Coxsackie B infections are not uncommon in the practice of a general medical unit and that they may account for more cases of both acute and subacute left chest pain than is usually realised.

Adolescent↗
PubMed1982

The testis and its excurrent ducts in American caenolestid and didelphid marsupials.

The present study examines and compares the structure of the testis and its excurrent ducts in a caenolestid and four didelphid marsupials. Of particular interest was the site of sperm pairing in the epididymis and whether this feature, shared by both American marsupial families but not by any Australian marsupial, was associated with changes in the morphology of the duct. In contrast to the testes of most Australian marsupials, except the peramelids (bandicoots), the intertubular space in the American marsupials was filled by Leydig cells (around 20% of testis volume). The opossum testes were unusual compared with those of eutherian mammals in that histological sections of individual seminiferous tubules contained only a single cellular association irrespective of the length of the tubule sectioned. The rete testis, as in the Australian dasyurids (devil, quoll, etc.), was a simple branching duct system that arose deep within the testis and emerged as a single duct at the testicular hilus. This arrangement is completely different from that in Kangaroos and Australian possums, indicating a diversity of rete form in the marsupials similar to that seen in eutherian mammals. The rete emptied into a single, essentially straight, efferent duct that became convoluted towards the epididymis, where it formed a distinct structure adjacent to the caput epididymidis. The efferent ducts were highly variable in diameter and epithelial height, suggesting that the duct was not of uniform character along its length, or that the initial single duct had divided to form ducts of different characters. Sperm pairs were first seen in the proximal cauda epididymis, and their appearance was correlated with changes in the character of the duct and its epithelium. The distal ductus deferens of Caenolestes, in contrast to those of the didelphids and indeed all other marsupials, was a convoluted ampulla-like structure adjacent to the prostate gland. In the other marsupials the only accessory sex glands are a segmented prostate and bulbourethral glands.

Americas↗
PubMed1982

Ultrastructural evidence of the onset of testicular pathological conditions in the cryptorchid human testis within the first year of life.

Pathological fibrosis of testicular intertubular tissues may be evident in the cryptorchid testis of children 1 year old. A characteristic feature of such testes is massive collagen deposition, which disrupts the regular order of the interstitium, in particular the peritubular layer of cells, by the time the child is 4 years old. These conclusions are based on ultrastructural examination of testicular biopsies collected at orchiopexy from 13 boys with cryptorchidism between 1 and 13 years old. These findings persuade us that orchiopexy should be performed in children about 1 year old and, certainly, no later than 2 years. Otherwise, eventual normal testicular function is highly unlikely.

Adolescent↗
PubMed1982

Abnormal aortic valve echoes in mitral prolapse. Echocardiographic features of floppy aortic valve.

The following distinctive combination of M-mode and two dimensional echocardiographic abnormalities of the aortic valve was observed in a group of 12 patients, of whom 11 had mitral valve prolapse. On two dimensional scans, the aortic cusps were freely mobile but appeared thickened or folded. On M-mode records, cusp excursion was normal: there was well defined systolic oscillation, and cusp echoes were multiple and centrally positioned within the aortic root during diastole. The aortic valve was inspected at operation in two patients: a typically myxomatous valve was replaced in one and findings were in keeping with this diagnosis in the other. It is suggested that the echocardiographic features described are characteristic of the floppy aortic valve. Despite the echocardiographic abnormalities, only three patients had clinical evidence of an aortic valve lesion. It is, therefore, further suggested that the investigation of patients with mitral prolapse should include echocardiographic assessment of the aortic valve, even when associated myxomatous degeneration of that valve is not suspected clinically.

Adolescent↗
PubMed1982

Induction of oestrus, recovery of gametes, and the timing of fertilization events in the opossum, Didelphis virginiana.

Of 14 lactating opossums maintained in laboratory conditions, 13 mated 4.7-8.5 days after removal of pouch young. The time between this removal and onset of receptive oestrus was negatively correlated with the age of the pouch young. Mating generally occurred between 24:00 and 06:00 h, with ovulation following between 13:00 and 16:00 h. Each animal ovulated a mean of 29.6 eggs (range 19-40), approximately equal numbers coming from both ovaries. Spermatozoa were absent from the uterus and were present only in the oviducts during the periovular period. Those not cleared by flushing (1-160 x 103/oviduct) remained incarcerated in isthmic crypts lined by a simple cuboidal epithelium. Spermatozoa in crypts were paired, separating or single. The progressively motile cells flushed from the oviduct presented a similar pattern to that in the crypts, about 30% of spermatozoa were firmly paired, the others either loosely associated or single. Only single spermatozoa attached to ova. Monospermic fertilization followed shortly after ovulation, and no supplementary spermatozoa were present in the perivitelline space. Deposition of the mucoid layer on the zona pellucida then began, often before incorporation of the fertilizing spermatozoon by the vitellus was complete. The oviducal epithelium was formed throughout by ciliated and secretory cells. In the ampulla and upper isthmus, the secretory cells produced the mucoid material which formed a thick coat over the egg surface. Ovum transit through the oviduct was rapid, in one animal eggs had reached the uterus and acquired a shell within 15-20 h of ovulation.

Animals↗
PubMed1980

Cardiac ultrasound.

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Cardiomyopathies↗