Long-term antibody synthesis in vitro. VI. Anti-allotype sera as probes of clonal products in affinity maturation.

A new experimental system is described for measuring the allotypic product of rabbit B cells during long-lasting in vitro antibody responses. The immunoenzymatic assays described allow determination of several parameters mapping in different regions of the same molecule, which can be measured and combined to yield a multidimensional picture of the time-course dynamics of antibody synthesis. The rabbit immune system responding to Escherichia coli beta-D-galactosidase was sample and disassembled by (a) culturing lymph node microfragments and (b) sorting out from among all anti-enzyme antibodies only those activating a mutant enzyme, AMEF, which bore the b4 or b9 allotype. A considerable simplification of the response was achieved in the microcultures as documented by cultures of heterozygous cells which produced only one allotype and by the fact that each culture showed a distinctive pattern when antibody titre, association constant, heterogeneity index, L-chain type, and k-chain allotype were considered together. This array of patterns was not an artifact but the result of disassembling a representative sample of the rabbit immune system into small components, since the b4/b9 ratio obtained by averaging the results of all cultures from a heterozygous rabbit lymph node was the same as the serum ratio. Despite the Poisson distribution of the responder microcultures, none of them was monoclonal; i.e. no antibodies homogeneous by all parameters tested were observed, This finidng supports the notion that in normal lymphoid tissue in its native tridimensional arrangement, one T cell can trigger several B cells clustered in one antibody-forming unit. This natural arrangement would ensure the monospecificity of the cluster (dictated by the T cell) while allowing for variation in affinity (depending upon the array of B cells in the unit). Accordingly our findings would results from the fact that as the size of the microfragments was reduced, the cells diluted out first were T cells, but as long as one of them was present, several B-cell clones were triggered. The b4/b9 pattern of any given culture remained constant over several months, but the ratio kappa/lambda underwent changes. An increase in molecules with non kappa-chains (which could not be reacted with anti-kappa-chain allotype antisera) was usually associated with a parallel decrease in antibody affinity. This occurred by the end of the antibody cycle and might be related to the regulation of antibody synthesis by T-cell suppressor factors.     

Anaesthesia for Caesarean section in a patient with Watson’s syndrome

Watson’s syndrome is an uncommon genetic disorder whose features include mental retardation and pulmonary valvular stenosis. The purpose of this report is to describe one management strategy used successfully to anaesthetize a woman with this disorder who presented for Caesarean section. Epidural anaesthesia using 0.5% bupivacaine without epinephrine in 2–3 ml boluses to a total dose of 15 ml was administered over 30 min. Invasive haemodynamic monitoring in the form of arterial and central venous catheters were used to guide therapy and help ensure maternal and fetal well-being. Intravenous ketamine in doses of 10–20 mg every five minutes to a total dose of 245 mg (4.5 mg · kg^?1) was used to overcome the patient’s uncooperative nature and facilitate invasive procedures. Postoperative analgesia was provided using 3 mg epidural morphine. The patient was observed in the intensive care unit for the first postoperative day and experienced an uncomplicated intra- and postoperative course. We conclude that this technique represents a safe and effective method for anaesthetizing patients with this complicated problem for Caesarean section.     

A comparison of the haemodynamic effects of intrathecal meperidine,meperidine-bupivacaine mixture and hyperbaric bupivacaïne

Purpose

To study the haemodynamic effects of intrathecal meperidine, administered either alone or mixed with bupivacaïne.

Methods

We studied 42 Chinese patients, aged 59–87 yr, scheduled for transurethral bladder or prostate surgery, randomized into three equals groups, that received either meperidine 0.8 mg · kg^{?1 meperidine 0.4 mg} · kg^?1 plus 1.5 ml of 0.5% heavy bupivacaïne or 3 ml of heavy bupivacaïne 0.5%. Non-invasive systolic (SAP) and mean (MAP) arterial pressures, central venous pressure and cardiac index, stroke index and heart rate (HR) measured by the BoMed NCCOM3-R7S bioimpedance device, were recorded over the first 25 min. Systemic vascular resistance index (SVRI) was derived. Onset of sensory and motor block was also measured. Decreases in MAP of 25% were treated with colloid and metaraminol. Results: The onset of block was slower in the meperidine group (P < 0.05). Decreases in SAP, MAP and SVRI (all; P < 0.001) occurred within five minutes in all three groups. The HR was increased in the bupivacaïne group (P = 0.03), but bradycardias treated with atropine occurred in six patients receiving meperidine and four patients receiving the mixture. Six patients receiving meperidine and two patients receiving the mixture required general anaesthesia for inadequate block. The incidence of nausea and vomiting was higher in the patients receiving meperidine (P < 0.05). No other complications were encountered.

Conclusions

Intrathecal meperidine used alone or mixed with bupivacaïne has no intra-operative advantage over heavy bupivacaïne 0.5%.     

Film loan policies of radiology departments

Last year, the AHRA Southern Region Statistical Resource Committee surveyed its members about their departments' film loan policies. This article presents the results of that survey, providing information on such topics as lending original films, charging for copies, and protecting against liability. While there doesn't seem to be a standard approach to releasing films, survey findings suggest that liability issues and cost factors are of great concern in determining which policy should be adopted.     

AHRA survey. Staff utilization: Part I

Part I of this AHRA membership survey reports on information relating to staff utilization in diagnostic radiology. The average volume of procedures per full-time-equivalent staff is provided for technologists, physicians, clerical staff and transporters. Part II, to be published in the Summer issue, will provide reports on specialty areas in radiology.     

AHRA survey. Staff utilization: Part III

Part III is the final installment of the 1993 AHRA membership survey on staff utilization and includes results for radiation therapy, nuclear medicine, interventional/angiography and cardiac catheterization. The information includes the volume of procedures and numbers of FTEs in departmental areas and comparisons with results reported from a similar survey of AHRA members conducted in 1989.     

Multicentre analysis of treatment planning information: Technical requirements,possible applications and a proposal

Digital data from 3‐D treatment planning computers is generally used for patient planning and then never considered again. However, such data contains enormous quantities of information regarding patient geometries, tissue outlining, treatment approaches and dose distributions. Were such data accessible from planning systems from multiple manufacturers, there would be substantial opportunities for undertaking quality assurance of radiotherapy clinical trials, prospective assessment of trial outcomes and basic treatment planning research and development. The technicalities of data exchange between planning systems are outlined, and previous attempts at producing systems capable of viewing and/or manipulating imaging and radiotherapy digital data reviewed. Development of a software system for enhancing the quality of Australasian clinical trials is proposed.     

Applied behavior management and acquired brain injury: approaches and assessment

Individuals who have acquired brain injury (ABI) may express themselves through the use of challenging behaviors, such as aggression, withdrawal, disinhibition, and self-destructive behaviors. This article describes the effectiveness of behavior interventions derived from the assessment of behavior in a community-based setting. The premise is that behavior, no matter how difficult, has function, purpose, and meaning for the individual. A therapeutic model of behavior assessment is presented that bases its strength on behavior assessment and well-trained staff. A well-formulated behavior management plan is developed, reinforcing alternative behaviors teaching skills, and reducing unwanted behaviors. Through the use of data collection methods, the treatment team identifies variables related to unwanted behavior and outcomes of consequences as they relate to the behavior. Illustrated through a case study, the behavioral treatment model is defined through behavior identification, initial assessments, treatment approaches, and tracking outcomes.