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Biomedical subjects

A J Cunningham

Publications and source records attributed to A J Cunningham.

At least 91 records · Page 5Linked to original sources
PubMed1982

The effect of metocurine and metocurine-pancuronium combination on intraocular pressure.

Maintenance of a normal to low intraocular pressure during ocular surgery is of critical importance. The prime considerations for anaesthetic management include adequate depth of anaesthesia, normal carbon dioxide and arterial oxygen tensions, stable cardiovascular status and avoidance of stimuli likely to raise central venous pressure. Non-depolarizing muscle relaxants are associated with a reduction in intraocular pressure. Metocurine, a non-depolarizing relaxant, formerly known as dimethyltubocurarine, has been recently reintroduced into clinical practice. Metocurine has been reported to be 1.8 times more potent than d-tubocurarine and has the clinically advantageous cardiovascular effects of stable heart rate and mean blood pressure with minimal associated histamine release. When combined with pancuronium, metocurine potentiates the neuromuscular blocking properties, so that small doses of both drugs in combination produce effective neuromuscular block. This study was designed to assess the suitability of metocurine 0.3 mg.kg-1 and metocurine 0.08 mg.kg-1 plus pancuronium 0.02 mg.kg-1 as muscle relaxants for ocular surgery. The results demonstrated that metocurine and metocurine-pancuronium combination in the above doses combined with sodium thiopentone 5 mg.kg-1 produced ideal conditions for intubation of the trachea in 4.45 (+/- 0.19 SE) minutes and 4.35 (+/- 0.16 SE) minutes respectively. In both treatment groups intraocular pressure was reduced below control values and a pattern of intraocular pressure stability ideal for ocular surgery was obtained during the 10 minutes observation period. The delayed onset of sufficient paralysis for tracheal intubation - 4.45 (+/- 0.19 SE) minutes for metocurine and 4.35 (+/- 0.16 SE) minutes for the combination - makes these techniques unsuitable for emergency ocular surgery because of the long interval when the airway is unprotected.

Adolescent↗
PubMed1982

Role of antibody in the protection of mice from arthritis induced by Mycoplasma pulmonis.

C3H and C57Bl10 mice exhibit a differential susceptibility to arthritis induced by Mycoplasma pulmonis. Resistant C57Bl10 mice consistently demonstrated higher complement-fixing antibody titres than susceptible C3H mice throughout the development of the acute arthritis. A strong correlation was demonstrated between the levels of anti-mycoplasma antibody and resistance to acute arthritis in six strains of mice. To test the hypothesis that the difference of arthritis resistance of C3H and C57Bl10 mice was caused by a different susceptibility of their lymphocytes to mitogenic stimulation by M. pulmonis, we investigated the generation of non-specific immunoglobulin in vivo and in vitro. M. pulmonis acted as a polyclonal mitogen, but stimulated approximately equal responses in lymphocytes of both strains.

Animals↗
PubMed1981

The effect of intravenous diazepam on rise of intraocular pressure following succinylcholine.

Because succinylcholine raised intraocular pressure, its use to facilitate tracheal intubation for ocular surgery, especially in emergency open-eye cases, has been a controversial topic among anaesthetists for more than two decades. In recent years, intravenous diazepam pretreatment before succinylcholine has been reported to reduce the untoward side effects of myalgia, and elevation of serum potassium and creatine phosphokinase. This study was designed to assess the effect of pretreatment with intravenous diazepam 0.1 mg kg-1 on control (base-line) intraocular pressure and to determine if such pretreatment diminished the rise in intraocular pressure following the standard anaesthesia induction sequence of thiopentone 3 - 5 mg kg-1., followed by tracheal intubation. Such diazepam pretreatment was shown to reduce the intraocular pressure from control levels and to diminish the rise of intraocular pressure following succinylcholine and tracheal intubation. Because succinylcholine produces rapid onset of neuromuscular block for tracheal intubation and since only minor intraocular pressure elevation occurs following thiopentone and succinylcholine in patients pretreated with diazepam, its use in ocular surgery, including emergency open-eye cases, can be rationally advocated. The addition of 0.6 mg kg-1 d-tubocurarine to the diazepam pretreatment did not produce a further reduction of the increase of intraocular pressure following succinylcholine.

Adult↗
PubMed1981

Ontogeny of the autoimmune reaction in normal mice to antigens in erythrocytes and gut.

Normal mice have large numbers of cells (PFC) making antibody to an autoantigen which is exposed when their own erythrocytes are treated with proteolytic enzymes. Antibody against this antigen can be demonstrated in serum by haemolysis tests against the treated cells; this antibody rises to high levels within 2 to 3 days after injection of E. coli lipopolysaccharide. using quantitative absorption tests we have located the 'bromelain mouse' (BrM) autoantigen in the gastrointestinal tract as well as in erythrocytes; this distribution pattern resembles that of classical blood group antigens. We have described the ontogenetic development of PFC, B cells capable of activation by LPS, serum antibody and antigen. Free antigen is found in the gut shortly after birth. B cells rise rapidly to high levels in the peritoneal cavity, but require a short period of culture to release detectable antibody. PFC and B cells increase more slowly in spleen to adult levels by 3 weeks of age. The serum antibody lags behind PFC development. The pattern is consistent with an early stimulation of B cells in the peritoneal cavity by gut-derived antigen. We discuss the possible relationship of this autoimmune response to high natural responses against other autoantigens in mice, man and other species.

Animals↗
PubMed1980

Individual-specific (idiotypic) T-B cell interactions regulating the production of anti-2,4,6-trinitrophenyl antibody. I. Generation of suppressor T cells and antibody directed against immunocompetent cells.

It is known from several experimental systems that the production of dominant antibody idiotypes may be regulated by anti-idiotypic mechanisms. Our aim has been to test whether the potential for such control also exists in the more typical heterogeneous antibody responses of inbred mice to the trinitrophenyl (TNP) hapten, where dominant idiotypes are not recognized. CBA mice were hyperimmunized to trinitrophenylated keyhole limpet hemocyanin. Serum or lightly fixed spleen cells from these mice were injected into normal syngeneic "recipients". The serum and spleen cells from these recipients were found to have the power to suppress in vitro anti-TNP antibody responses made by further spleen cells from the donor mice. This suppression was specifically directed against the cells of the individual donor animals suggesting idiotype-related regulation.

Animals↗
PubMed1980

Individual-specific (idiotypic) T-B cell interactions regulating the production of anti-2,4,6-trinitrophenyl antibody. II. Development of idiotype-specific helper and suppressor T cells within mice making an immune response.

The previous report demonstrated that serum and cells from CBA mice immunized with trinitrophenyl (TNP), when injected into normal, syngeneic "recipient" mice, induce the formation of apparently idiotype-specific suppressor cells and serum factors, and that such regulatory elements develop within the serum of the TNP-immunized animals themselves. In this report, it is indicated that regulator cells develop also within the spleens of TNP-keyhole limpet hemocyanin-immunized animals, and may in part be responsible for our earlier observation that T cells from TNP-immune CBA mice stimulate optimal antibody production in culture when paired with B cells from the same individual animal. While some evidence for individual-specific T helper cells was obtained, the poorer response of mismatched T and B cells could be attributed in part to Ly-2.2-bearing suppressor T cells. Overall, the results support the view that idiotype-related regulation is not confined to dominant-idiotype models but is also involved in heterogeneous anti-hapten antibody responses.

Animals↗
PubMed1980

Restriction of antigen recognition in mouse B lymphocytes by genes mapping within the major histocompatibility complex.

B cells, like T cells, show genetic restrictions in their interactions with other cells. B cells from (C3H/HeJ X C57BL/6J)F1 mice were stimulated with foreign antigen (sheep erythrocytes, SRBC) in parental-strain irradiated hosts. They could be subsequently activated to antibody formation in vitro by SRBC presented on cells of the same parental type, and much less by SRBC on cells of the other parental type. The restriction was seen whether antigen was presented on macrophages or by activated T cells. Experiments with congenic mice showed that the restriction was controlled by the MHC locus. Restriction of F1 B cells to responsiveness against either parental haplotype was much more readily induced in bone marrow than in splenic populations. This restriction could be broken down by giving the irradiated host a second injection of antigen 3 weeks after the first; this probably reflects "reeducation" of the F1 B cells by SRBC associated with donor, F1-type macrophages. Normal unprimed spleen B cells also showed a strong preference for activation by SRBC in association with syngeneic activated T cells.

Animals↗
PubMed1978

Requirement for matching T cell and B cell subsets in secondary anti-hapten antibody responses.

The in vitro secondary anti-hapten response to trinitrophenylated keyhole limpet hemocyanin (TNP-KLH) has been investigated using B and T cells from the same or a pool of identically primed syngeneic individuals. The optimum antibody response obtained from B cells of any given animal was seen when the same individual's T cells were used as a helper cell source. This individual preference was lost if secondary challenge in culture was made with TNP on a heterologous carrier, with the helper cells obtained from suitably primed individuals or a pool thereof. These data are interpreted in terms of a network theory for the regulation of immune responses under physiological conditions.

Animals↗
PubMed1977

Ontogeny of the antibody-forming cell line in mice. III. The generation of mature anti-sheep red blood cell-specific B cells is antigen-dependent.

A role for antigen in the generation of fully mature splenic type B cells has been shown. In adoptive transfer experiments, cells from bone marrow or fetal liver required a longer period to give an anti-sheep red blood cell plaque-forming cell (PFC) response than those from spleen. This delay was not overcome by allowing the cells a 7-day sojourn in the irradiated host before antigen challenge. A two-stage protocol was designed in which the in vivo generation of fully mature cells could be measured by their ability to give PFC in lipopolysaccharide-stimulated cultures in vitro. These experiments showed that a critical factor which influences the final differentiation of bone marrow or fetal liver cells into mature, splenic type B cells is exposure to antigen.

Animals↗