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Biomedical subjects

G Morgan

Publications and source records attributed to G Morgan.

At least 343 records · Page 19Linked to original sources

Immunological investigations in post-traumatic granulomatous and non-granulomatous uveitis.

Histopathological and immunological investigations have been performed in 16 cases of post-traumatic granulomatous (10) and non-granulomatous uveitis (6). Most cases of sympathetic ophthalmitis showed evidence of cell mediated immunity to uveoretinal antigens, though it was not possible to make a definitive diagnosis on immunological grounds alone. Three patients with post-traumatic non-granulomatous uveitis showed a positive immunological response to ocular antigens, and 2 of these later developed clinical evidence of sympathetic ophthalmitis, which suggests that post-traumatic non-granulomatous uveitis in such cases may represent a presympathetic (i.e., incipient) or modified stage of the disease.

Antigens↗

Lymphocytic tumours of indeterminate nature: a 5-year follow-up of 98 conjunctival and orbital lesions.

Ninety-eight adnexal lymphocytic tumours of indeterminate nature have been followed up for at least 5 years. Both non-disseminating and disseminating tumours have either very similar or identical histopathological features. It is not possible to make a definitive diagnosis when the lesions are first seen, and a conclusion can be reached only after a prolonged follow-up. The nature of the non-disseminating tumours is unknown.

Adolescent↗

"Sunbursts" and "christiesomes": cellular fragments in normal cow and goat milk.

Goats' milk includes numerous cell fragments ("christiesomes") which originate from the mammary secretory cells, contain well preserved endoplasmic reticulum, mitochondria and lipid droplets, and are responsible for the considerable triglyceride synthesising capacity of fresh goat milk. Cows' milk shows a few such particles only after repeated oxytocin-aided milkings. Cows' milk does contain quite different particles which have a dense content with a few small vesicles and numerous microvillus-like protrusions on one side ("sunbursts"). These have not been found in goats milk. Cytoplasmic particles similar to sunbursts have been found on the surface of the mammary secretory epithelium. It is suggested that they are residues of dead cells.

Animals↗

A simplified approach to the treatment of hypertension.

A new beta-adrenoreceptor blocking drug (timolol) was used in two clinical studies. In the first double blind study administration of hydrochlorothiazide and timolol reduced the mean (formula: see text) blood pressure by 23 mm Hg, compared with a fall of nine mm Hg with administration of hydrochlorothiazide and a placebo. Plasma potassium (K+) levels fell with the administration of hydrochlorothiazide alone, but rose back to control values when patients were given timolol. In the second study (patient blind), Moduretic (hydrochlorothiazide, 50 mg and amiloride, 5 mg) and timolol were given once daily. The mean blood pressure fell by 20 +/- 2 mm Hg allowing hypertension to be controlled by this once-daily regimen; the control persisted throughout the day. Plasma potassium (K+) levels fell slightly after treatment with Moduretic, but the fall was not as great as with hydrochlorothiazide. Of the 65 patients who entered these studies, 35 had not been previously treated and had diastolic blood pressure between 105 mm Hg and 130 mm Hg. In 18 patients the diastolic blood pressure was reduced below 95 mm Hg after treatment with a diuretic alone, in 15 patients treatment with a diuretic and timolol (5 mg to 20 mg) reduced the diastolic blood pressure below 95 mm Hg. In two patients, the diastolic blood pressure was between 95 mm Hg and 100 mm Hg. The response achieved with a relatively simple therapeutic regimen that can be administered once daily suggests that the therapy of most hypertensive patients could be supervised by paramedical personnel.

Adult↗

Previous pregnancy as a protective factor against death from melanoma.

Examination of the case-records of women presenting to the Melanoma Unit at Sydney Hospital over the period 1961-71 has shown that women with pregnancies before the development of melanoma had a better survival-rate from melanoma than women without previous pregnancies. The known presence of fetal antigens on melanoma cells and immunisation against fetal antigens during pregnancy suggest an immunological explanation for these results. Exposure to fetal antigens during pregnancy may protect against the dissemination of melanoma cells bearing similar fetal antigens and thus increase the survival-rate. The incidence of melanoma in males and females was approximately equal, which suggests that immune responses to tumour-associated antigens may be more effective in preventing spread of tumours than in preventing their occurrence.

Adult↗

Squamous cell carcinoma developing in an orbital cyst.

A squamous cell carcinoma developed in the wall of an orbital cyst in a 53-year-old man. There was a vague history of previous injury, which was probably of no significance, and there was no evidence of any dermal elements in the cyst wall. The case appears to be unique because it most probably had its origin in a congenital epidermoid cyst.

Bone Cysts↗

Detection of carcinoembryonic-like antigen on melanoma cells by leucocyte-dependent-antibody assays.

CEA-like antigen has been detected on the surface of some melanoma cells using a rabbit antiserum raised against CEA antigen in 51Cr-release leucocyte-dependent cytotoxic-antibody (LDA) assays. The CEA antigen used for production of the antiserum was shown to be immunologically pure by immunoelectrophoresis procedures and reacted with a reference serum to CEA. The specificity of the CEA antiserum for CEA on the melanoma cells was further shown by removal of reactivity to melanoma cells after absorption on CEA affinity columns. LDA activity to CEA was also shown in a serum taken during pregnancy. No CEA LDA activity was found in several melanoma sera. These findings suggest that CEA may have biological significance in tumour rejection, and that CEA assays may be of value in monitoring disease activity in melanoma patients.

Animals↗

Cell replacement and changing transport function in the neonatal pig colon.

1. Measurements of intracellular methionine concentration in pig colon, following in vitro incubation in methionine containine medium, have been carried out during the first 10 days of post-natal life. 2. The new-born pig colon concentrates methionine within its mucosa. Autoradiography of 3H-labelled phenylalanine shows it to be accumulated to greatest extent in cells located in the surface epithelium. 3. The ability of the colonic mucosa to concentrate methionine disappears during the first few days of post-natal life. 4. Radioactive thymidine, injected at birth, shows cell mitosis to be confined to the lower third of each colonic crypt. Labelled cells later migrate out of the crypts on to the surface epithelium. The cell replacement time is 105 h. 5. The time course for the fall in the ability of the pig colon to actively accumulate methionine corresponds to that predicted if cells synthesized from birth were unable to transport this amino acid. 6. The ability of the new-born pig colon to transport amino acids, though transient, may be physiologically important. The nature of the signal which changes the physiological function of cells synthesized post-natally remains to be determined.

Age Factors↗

Immunopathology of the lens. I. Humoral and cellular immune responses to heterologous lens antigens and their roles in ocular inflammation.

In experimental rabbits heterologous soluble lens proteins consisting of alpha-, beta-, and gamma-crystallins were found to be antigenic; they stimulated a marked antibody response compared to a rather weak T-cell response. The serum antibodies to alpha-crystallins appeared first, to be followed by antibodies to beta- and gamma-crystallins in that order. The rabbits did not respond to heterologous gamma-crystallins unless these were injected with Freund's adjuvant containing mycobacteria. Incomplete Freund's adjuvant (i.e., without mycobacteria) was found to be an inferior immunoaccelerator so far as lens antigens are concerned. The response to lenticular antigens in both magnitude and duration varied in different rabbits, which suggested to us the important role played by a central control mechanism involving the immune response (Ir) genes. Some of the antibodies in potent lens antisera cross-reacted with mitochondria, endoplasmic reticulum (i.e., microsomes), contractile organelles, and cell nuclei. This explains for the first time at least in part the reasons for the widely observed phenomenon of the reactivity of lens antisera with ocular and extraocular structures. Antibodies to soluble lens proteins as detected by immunofluorescence and immunoperoxidase techniques were shown to be of the IgG class. Systemic heterologous immunisation followed by discission of the lens does not lead to the typical changes of phakoallergic endophthalmitis in the rabbit.

Animals↗

Histopathological changes in malignant melanomas of the choroid after cobalt plaque therapy.

A series of 23 eyes removed after cobalt plaque therapy for malignant melanoma of the choroid is presented, and the histological changes are described with particular reference to the presence or absence of necrosis in the tumours. In 17 of the 23 eyes no evidence of tumour necrosis was found, though all showed evidence of radiation changes in the adjacent tissues. Necrosis was found in 6 cases but was prominent in only 2, one of which was the only example of a mixed-cell tumour, the other 22 being spindle-cell tumours. Enucleation became necessary on average at about 32 months after treatment (23 out of 100 treated eyes) because of obvious failure of treatment with evidence of continued growth, or because of radiational complications leading to a painful blind eye. The 5-year survival rate was 86% compared with about 50% when the treatment is enculeation.

Adult↗

Immunopathology of the lens. II. Humoral and cellular immune responses to homologous lens antigens and their roles in ocular inflammation.

It has been possible for the first time to demonstrate antibodies to homologous lens proteins in rabbits without the addition of adjuvant. By means of immunofluorescence and immunoperoxidase methods it has been possible not only to show for the first time that homologous lens antibodies cross-react with extraocular tissues but that the cross-reacting antigens are related to the cell mitochondria, microsomes, and the proteins associated with contractile organelles. The rabbits did not produce antibodies to gamma-crystallins even when the whole lens homogenate was injected with Freund's complete adjuvant. This suggests that gamma-crystallins are non-antigenic in homologous situations, and this may be related to both B- and T-cell tolerance. Alternatively, the failure of gamma-crystallins to induce antibody production may be due to intermolecular antigenic competition with other crystallins. The presence of mycobacteria in an adjuvant is essential for an antibody response to be detectable by agar diffusion techniques. The response to homologous lens antigens, both in magnitude as well as in duration, varied in different rabbits, which suggested to us that a central control mechanism involving the immune response (Ir) genes may plan an important role. Antibodies to homologous lens proteins as detected by immunofluorescence and immunoperoxidase methods were shown to be of the IgG class. This is the first time that the kinetics of the immune response to the same homologous lens antigen in saline with or without incomplete or complete adjuvant has been examined and their relative merits compared. Systemic homologous immunisation followed by discission of the lens led to a marked Arthus type reaction in and around the lens, but a typical granulomatous phakoallergic endophthalmitis was not produced. It seems likely that the rabbit is not suitable for the production of an experimental model of this condition.

Adjuvants, Immunologic↗

Immunopathology of the lens. III. Humoral and cellular immune responses to autologous lens antigens and their roles in ocular inflammation.

In experimental rabbits it has been shown for the first time that autologous lens protein is antigenic when injected with Freund's complete adjuvant. Although lens haemagglutinins were detected in 6 out of 7 rabbits, in only 3 of the 6 animals did the titre reach a maximum of 1:640. A weak agar precipitation reaction was obtained with only 1 of the 3 sera. It would appear, therefore, that the passive haemagglutination test is superior for the detection of autologous lens antibodies. The response to autologous lens antigen both in magnitude as well as in duration varied in different rabbits, which suggested to us the possible role played by a central control mechanism involving the immune-response (Ir) and immune-associated (Ia) genes which are part of the major histocompatibility complex. Alternatively, this variation may be the result of an antigenic competition between various autologous crystallins. Antibodies to autologous lens protein as detected by immunofluorescence and immunoperoxidase techniques were shown to be of the IgG class. Systemic autologous immunisation produces only a mild uveitis and does not lead to a granulomatous intraocular inflammation. Intravitreal injections of autologous lens protein in pre-immunised animals, however, produced an Arthus type of acute endophthalmitis. Autologous lens antisera showed limited cross-reactivity with ocular and extraocular tissues, which could be detected only by such sensitive techniques as immunofluorescence and immunoperoxidase methods.

Animals↗