Racial Identity Attitudes and Vicarious Traumatization from Undue Police Violence on Anticipatory Traumatic Reaction Among Black Americans

Although the viral nature of videos that capture violent and racialized policing of Black Americans in the United States can increase awareness, exposure to race-based violence can result in vicarious traumatization, particularly among Black Americans. The relationship between anticipatory traumatic reactions (ATRs) and racial identity attitudes is not clearly addressed in the extant body of literature. The current study addresses this research disparity by first analyzing group mean differences among Black Americans (N = 138) who were assigned to audiovisual, written, and imaginal exposure groups. The current study also used a cluster analysis of Black Americans to examine the differences between racial identity attitudes and ATRs following media exposure to undue police violence. Results from the study indicated that no differences in ATRs existed based on types of media exposure. Significant differences across three racial identity clusters existed between ATR in association with attitudes of assimilation, miseducation, self-hatred, anti-dominance, and ethnic-racial salience. Findings from the study suggest that mental health professionals should attend to racial identity attitudes as a relevant factor in how Black American clients experience the psychological impact of media exposure to undue police violence.

873 The Keystone Challenge- Volar Displaced Intra-Articular Distal Radius Fractures with Lunate Fossa Fragment

Aim

Volar displaced fractures of the distal radius are unstable and warrant operative management. A subset of patients with volar displaced fractures also has a separate lunate fossa fragment, a specific injury with greater instability that may precipitate carpal subluxation. We aim to review our long-term experience in the management of this complex injury, exploring surgical technique which may improve treatment.

Method

We retrospectively reviewed all volar displaced distal radius fixations between 2015 and 2020. Inclusion criteria: any displaced intra-articular volar distal radius fracture with lunate fragment involvement undergoing volar fixation and over 16 years of age. Exclusion criteria: shaft fractures, extra-articular fractures, open fractures, fractures fixed using k-wires or external fixation, revision surgery and patients without follow-up. We adapted our surgical approach in order to address this more complex fracture pattern, and all operations were performed by specialist hand surgeons.

Results

468 distal radius fractures were assessed, of which 29 (6%) cases included a lunate fossa fragment. 20 (69%) of patients were female, mean age was 59 years (SD 12.4). Mean length of stay was 5 hours and mean operative time was 96 mins (range 79-95). No patients had carpal subluxation, fracture fixation failure or return to theatre for any reason.

Conclusions

From our experience as a specialist orthopaedic institution, we recommend the extended FCR approach and intra-focal exposure to manage this complex injury. In particular, the lunate fossa fragment is the keystone which requires dedicated reduction prior to tackling the remaining fracture configuration.

The Drosophila MLR COMPASS-like complex regulates bantam miRNA expression differentially in the context of cell fate

The conserved MLR COMPASS-like complexes are histone modifiers that are recruited by a variety of transcription factors to enhancer regions where they act as necessary epigenetic tools for enhancer establishment and function. A critical in vivo target of the Drosophila MLR complex is the bantam miRNA that regulates cell survival and functions in feedback regulation of cellular signaling pathways during development. We determine that loss of Drosophila MLR complex function in developing wing and eye imaginal discs results in growth and patterning defects that are sensitive to bantam levels. Consistent with an essential regulatory role in modulating bantam transcription, the MLR complex binds to tissue-specific bantam enhancers and contributes to fine-tuning expression levels during larval tissue development. In wing imaginal discs, the MLR complex attenuates bantam enhancer activity by negatively regulating expression; whereas, in differentiating eye discs, the complex exerts either positive or negative regulatory activity on bantam transcription depending on cell fate. Furthermore, while the MLR complex is not required to control bantam levels in undifferentiated eye cells anterior to the morphogenetic furrow, it serves to prepare critical enhancer control of bantam transcription for later regulation upon differentiation. Our investigation into the transcriptional regulation of a single target in a developmental context has provided novel insights as to how the MLR complex contributes to the precise timing of gene expression, and how the complex functions to help orchestrate the regulatory output of conserved signaling pathways during animal development.

Adult distal radius fractures classification systems: essential clinical knowledge or abstract memory testing?

Classification systems should be tools for concise communication, which ideally can predict prognosis and guide treatment. They should be relevant, reproducible, reliable, properly validated and most importantly simple to use and understand. There are 15 described distal radius classification systems present in the literature in the past 70 years, of which 8 are discussed in this paper. For each classification, we give an insight into its history, strengths and weaknesses, and provide evidence from the literature on reliability and reproducibility. Sadly, on completion of this paper we have not found a distal radius fracture classification that proved to be useful. Failings range from poor reproducibility and reliability, and over-complexity mainly emanating from the inability to classify this spectrum of injury in all of its manifestations. Consequently, we would suggest that classification systems for acute adult distal radius fractures are not useful clinical knowledge but mainly historical and/or research tools. Moreover, we would discourage trainees from spending time learning these classifications, as they serve not as essential clinical knowledge but more as forms of abstract memory testing.

Giant Lipomatous Tumours of the Hand and Forearm

This study examines the presentation, management and outcomes of a series of 10 patients with giant lipomatous tumours (defined as greater than 5 cm diameter) of the hand and forearm who presented to our orthopaedic oncology service. All patients underwent local staging and were discussed at our multidisciplinary tumour meeting prior to definitive surgery. In all cases, neurovascular structures required mobilization in order to excise the tumour. Seven of the tumours were benign lipomas and one was a neural fibrolipoma. The other two were well differentiated lipoma-like liposarcomas/atypical lipomatous tumours. Giant lipomas and well differentiated lipoma-like liposarcomas/atypical lipomatous tumours of the hand and forearm present infrequently and a multidisciplinary approach is recommended in the investigation and surgical management of these patients.

One-year outcome for elderly patients with displaced intracapsular fractures of the femoral neck managed non-operatively

The outcome of patients with a displaced intracapsular femoral neck fracture treated non-operatively was assessed at 1 year and compared with patients managed operatively over the same time period. Data were collected prospectively for 102 consecutive patients. 80 patients underwent hemiarthroplasty and 22 were managed non-operatively. Patients were managed non-operatively if they were felt to have an unacceptably high risk of death within the perioperative period despite medical optimisation. Non-operative management entailed active early mobilisation without bed rest or traction. Patients managed non-operatively had a greater 30-day mortality compared with operatively managed patients. Deaths were due to pre-existing medical conditions or events, which had occurred at the time of hip fracture. No patient in the non-operative treatment group developed pneumonia, pressure sores or thrombo-embolic events. Patients treated non-operatively, who survived 30 days after fracture, had a mortality rate over the following year comparable with those who had undergone surgery. At 1 year, all non-operatively managed patients were able to transfer without pain and 6 of the 11 surviving patients were able to mobilise with walking aids. At 1 year, the majority of surviving non-operatively managed patients were living in their own homes. Surgical intervention is the treatment of choice for the majority of elderly patients with a displaced intracapsular femoral neck fracture. However, in patients with life-threatening medical co-morbidity, non-operative treatment with early mobilisation can yield acceptable results.

A cryoclamp for the rapid cryofixation of the isolated blood-perfused rabbit cardiac papillary muscle preparation at predefined times during the contraction cycle

There is increasing evidence that the distribution of monovalent cations in cardiac cells may be non-uniform, particularly in the region immediately beneath the sarcolemma, and we have proposed that a build-up of sodium in this region could be an important factor in the development of ischaemia-reperfusion injury. Electron probe X-ray microanalysis is ideal for the study of such changes in distribution but the application of the technique to this problem imposes severe requirements on the specimen and on the method for cryofixation. The specimen must be perfused through its vasculature so that it can be made truly ischaemic and be successfully reperfused. It is necessary to be able to cryofix the specimen without disturbance of its blood supply, electrical stimulation or temperature. It is also important to know the time in the contraction cycle when cryofixation occurs. Here we describe the design of an automated cryofixation device which can be used to cryofix a blood perfused papillary muscle preparation at predetermined time points in the contraction cycle. Preliminary data obtained from the analysis of rabbit papillary muscles subjected to varying periods of ischaemia are included as an example of the use of the cryoclamp.

Sale of cigarettes to school children aged 14 and 15 years in New Zealand

AIMS

To determine the sources of cigarettes and extent of illegal sales to 14 and 15 year old children, and to examine associated risk factors in order to more effectively reduce tobacco access to children.

METHOD

Nationwide cross sectional survey of fourth form school children in New Zealand by means of an anonymous self administered questionnaire.

RESULTS

Questionnaires from 14,097 fourteen and fifteen years olds were analysed, with over one third smokers. Twenty four percent of the whole group (3432) had bought cigarettes in the last year. Of smokers, 59.9% bought their own, with the great majority (68.9%) from dairies, particularly females. Ninety five percent said it was "easy" or "very easy" to buy cigarettes, and this was a major risk factor for this behaviour (relative risk (RR) = 2.01, 95% confidence interval (CI) 1.74, 2.32, RR = 2.54, CI 2.28, 2.83, respectively). Only 24.6% children had ever been refused cigarettes because of age and all points of sale were comparable in this respect. Heavy smokers and males were more likely to have been refused. While refusal was associated with a fourfold increase in the perception that it was difficult to buy cigarettes, there was only a minimal reduction in the risk of children buying their own cigarettes (RR = 0.95, CI 0.91, 1.00).

CONCLUSION

We have shown that the illegal sale of cigarettes to children is unacceptably easy and accurately perceived as such by children who smoke. The active enforcement of existing or future legislation is essential, with prosecution of offending retailers, if we are to make any progress to reduce the high prevalence of smoking in New Zealand children.

A national survey of cigarette smoking in fourth-form school children in New Zealand

AIMS

To determine the prevalence of cigarette smoking in 14 and 15 year old school children in New Zealand and to examine associated risk factors.

METHODS

Nationwide cross-sectional survey of fourth-form school children in New Zealand by means of an anonymous self administered questionnaire in November 1992.

RESULTS

Questionnaires from 14,097 fourteen and fifteen year-olds were analysed. 65.6% had tried smoking, and 36.1% regarded themselves as smokers. Females and Maori had significantly higher prevalence rates. Of Maori females 44.6% were current smokers (more than one per month) compared to 24.0% for the whole group, and 33.0% were daily smokers. Pacific Island students, who have similar socioeconomic disadvantage to Maori, have a lower relative risk of smoking (RR) 0.79, (95% confidence interval (CI) 0.68, 0.91), than Europeans. Major independent risk factors were identified and population attributable risk was calculated for parental smoking (22.9%), poor knowledge of adverse health effects (7.3%) and watching televised sports (13.4%). These three modifiable factors accounted for 36.1% of the total smoking prevalence in these children.

CONCLUSION

The continued high prevalence of smoking in New Zealand children, especially in Maori and in females, prove current public health measures to be inadequate. Our results suggest that strategies aimed at decreasing parental smoking, improving student knowledge of adverse health effects and preventing tobacco sponsorship of television sports could greatly decrease the smoking prevalence in this age group.

Immunomagnetic bone marrow purging of common acute lymphoblastic leukemia cells: suitability of BioMag particles

Immunomagnetic bone marrow purging is becoming a widely used technique in many bone marrow transplant centres. Most centres use Dynabead magnetic particles to facilitate the procedure. The suitability of a novel magnetic particle (BioMag) for immunomagnetic purging was addressed in this study. Common acute lymphoblastic leukemia (ALL) cells were targeted using CD9 and CD10 mouse monoclonal antibodies prior to attachment of magnetic particles coated with anti-mouse immunoglobulin and depleted with samarium cobalt magnets. Immunofluorescent and clonogenic assays capable of measuring more than four log depletions of the Nalm 6 cell line showed that a single cycle of purging reduced target cells by 3.1 +/- 0.9 BioMag particles and 1.8 +/- 1.0 logs with Dynabeads. A second cycle of purging was advantageous, increasing target cell depletions to more than 4.5 logs with either particle type. Bone marrow granulocyte-macrophage colony-forming units were not significantly reduced. The results indicate that BioMag particles can be used for the efficient depletion of common ALL cells from bone marrow for transplantation.

Fractures of the fifth metacarpal neck: is reduction or immobilisation necessary?

Sixty two patients with fractures of the neck of the little finger metacarpal have been studied. Treatment consisted of unrestricted exercises without any splintage or attempts at reduction, irrespective of the degree of angulation of the fractures. Patients were reviewed at one or two-weekly intervals until movement had recovered and return to work was possible. One year after injury, patients were recalled for examination. Recovery was rapid with no long-term functional restriction, although 14% of patients noted minor cosmetic deformity.

'Safe oxygen' in acute asthma: prospective trial using 35% Ventimask prior to admission

There is still some uncertainty as to the best inspired oxygen concentration to use in the treatment of acute asthma before measurement of arterial blood gases can be made. In the absence of published data, we report a prospective study in which 35% oxygen was the initial therapy given to patients with moderate to severe asthma, and arterial blood gases were taken to assess the adequacy of oxygenation and the safety of this method. Forty-five episodes were analyzed and a wide range of PaO2 was observed (8.8-21.3 kPa 66-160 mmHg). No relationship was shown between PaCO2 and either PaO2 or duration of oxygen treatment. It was concluded that 35% oxygen given in acute asthma is both safe and probably adequate. A lesser concentration of oxygen could expose asthmatics to an unacceptable risk of significant hypoxaemia.

Fractures of the fifth metacarpal neck: is reduction or immobilisation necessary?

Sixty two patients with fractures of the neck of the little finger metacarpal have been studied. Treatment consisted of unrestricted exercises without any splintage or attempts at reduction, irrespective of the degree of angulation of the fractures. Patients were reviewed at one or two-weekly intervals until movement had recovered and return to work was possible. One year after injury, patients were recalled for examination. Recovery was rapid with no long-term functional restriction, although 14% of patients noted minor cosmetic deformity.

Peripheral neurotoxicity of 2-chloroprocaine and bisulfite in the cat

The responses of peripheral nerves less than 6 hr after and 2 weeks after exposure to 2-chloroprocaine (2-CP) and bisulfite (BS) were studied in cats using electrophysiologic techniques and by light and electron microscopy. Three percent 2-CP with 0.07% or 0.2% BS was not toxic to peripheral nerves. Three percent 2-CP with 1.2% BS and 1.2% BS (pH 2.8) alone had an acute effect on the peripheral nerves but no chronic effect. Ten percent BS (pH 2.8) caused Wallerian degeneration. However, at pH 4.8, no chronic toxicity was observed. Using conductivity measurements, it was shown that 2-CP and BS, when mixed, form an ion pair in solution that lowers the effective concentration of BS.

Fractures of the metacarpals: treatment by A. O. screw and plate fixation

Twenty-two patients with 26 fractured metacarpals were treated by internal fixation using A. O. mini-fragment screws and plates. This form of internal fixation was reserved for metacarpal fractures which were multiple, unstable, displaced or rotated. Nine patients had open fractures, two had divided extensor tendons and four had multiple fractures. Fractures consistently united without infection or deformity. The mean duration of postoperative immobilization was seven days and mean time off work was six weeks. All but one patient did manual work. No patients had persistent symptoms which caused difficulty with work or sport. Fourteen patients regained full movement. Four had total active movement of 220 degrees or more in the involved ray and 6 patients had total active movement of between 180 and 220 degrees. Restricted movement was present in patients with open fractures and divided extensor tendons or intra-articular fractures of the metacarpal head. Uniformly satisfactory results were found after mini-screw and plate fixation of metacarpal fractures.

Fractures of the phalanges: results of internal fixation using 1.5mm and 2mm A. O. screws

Thirty-six patients were treated for 38 phalangeal fractures using 1.5 mm and 2 mm A. O. screws. Plates were not used in the fingers. Oblique fractures of the condyles, shafts or bases of the proximal or middle phalanges were treated by internal fixation because of instability, displacement or rotation. 40% of fractures had associated skin wounds, were comminuted or had damage to the extensor mechanism. The mean duration of post-operative immobilization was 9 days and the mean time off work was 6 weeks. Total active movement in the involved ray was 220 degrees or greater in 24 cases, 180 degrees to 215 degrees in eight cases, and less than 180 degrees in two patients at follow up. The patients were reviewed between three and 54 months after treatment and the mean duration of follow up was 24 months. The most frequent complication was 10 degrees to 30 degrees of flexion deformity of the proximal interphalangeal joint after internal fixation of condylar fractures. Results were satisfactory in 90% of cases.

Fractures of the Metacarpals: Treatment by A. O. Screw and Plate Fixation

Twenty-two patients with 26 fractured metacarpals were treated by internal fixation using A. O. mini-fragment screws and plates. This form of internal fixation was reserved for metacarpal fractures which were multiple, unstable, displaced or rotated. Nine patients bad open fractures, two had divided extensor tendons and four had multiple fractures.

Fractures consistently united without infection or deformity. The mean duration of postoperative immobilization was seven days and mean time off work was six weeks. All but one patient did manual work. No patients had persistent symptoms which caused difficulty with work or sport. Fourteen patients regained full movement. Four had total active movement of 220 degrees or more in the involved ray and 6 patients had total active movement of between 180 and 220 degrees. Restricted movement was present in patients with open fractures and divided extensor tendons or intra-articular fractures of the metacarpal head.

Uniformly satisfactory results were found after mini-screw and plate fixation of metacarpal fractures.

The Herbert screw for fractures of the scaphoid. A review of results and technical difficulties

We have reviewed 22 patients with scaphoid fractures treated by internal fixation with the Herbert screw. Three patients had trans-scaphoid perilunar dislocations, one had an oblique displaced fracture of the waist of the scaphoid and 18 had fractures with delayed or non-union. Corticocancellous bone grafts were added in nine of the cases of non-union. Results were excellent or good in 80% of cases after a mean duration of postoperative immobilisation of four weeks. The technical difficulties are analysed and the problems of applying the jig and of operative exposure are discussed.

Acute carpal tunnel syndrome. Complications of delayed decompression

Five patients suffered injuries around the wrist complicated by acute tunnel syndrome. Pain associated with median nerve paraesthesia or hypo-aesthesia are indications for urgent treatment; in four patients where operation was delayed, the outcome was poor.

Post mastectomy pain after brachial plexus palsy: metastases or radiation neuritis?

Three patients have been reported who developed metastatic tumour within the neural tissue of the brachial plexus three years, four years and fourteen years respectively after treatment of breast carcinoma by simple mastectomy and postoperative radiotherapy. A fourth patient who developed bilateral upper limb paralysis after radiotherapy for a lymphoma is also reported. At exploration of the brachial plexus extensive fibrosis was present in all cases with metastases only diagnosed through biopsy of neural tissue. The clinical features and the role of surgery are discussed in the light of our experience and a review of available literature.

Duration and toxicity of bupivacaine for topical anesthesia of the airway in the cat

To assess bupivacaine as a topical anesthetic of the airway, 0.5 ml of 1, 2, and 4% bupivacaine was sprayed down the trachea of lightly anesthetized cats and the duration of anesthesia, systemic toxicity, and local toxicity was compared to that produced by 4% lidocaine. Two percent bupivacaine suppressed the cough reflex longer than 4% lidocaine with no increase in either local or systemic toxicity. Four percent bupivacaine produced arrhythmias in 5 of 10 cats in two groups and apnea in 4 of 6 cats. This study indicates that 2% would be an appropriate concentration to assess bupivacaine as a topical anesthetic of the airway in humans.

Comparison of insulated and uninsulated needles for locating peripheral nerves with a peripheral nerve stimulator

This study was designed to compare the use of insulated and uninsulated needles with a peripheral nerve stimulator for locating a peripheral nerve in an anesthetized cat. The needles were mounted on a one-dimensional manipulator and both the saphenous and sciatic nerves were located. The tip of the insulated needle was consistently placed on the sciatic nerve. The tip of the uninsulated needle was placed 0.1-0.9 cm past the sciatic nerve. Injecting saline to assess the position of the tip of the needle relative to the sciatic nerve did not detect the needle being past the nerve. With the saphenous nerve preparation, both the needle and nerve were visible through the tissue. Using an insulated needle, the minimum current required to stimulate the nerve occurred when the tip of the needle touched the saphenous nerve. Using an uninsulated needle, the minimum current occurred when the tip was 0.1-0.8 cm past the nerve. The conclusion is that insulated needles more precisely locate the peripheral nerve than uninsulated needles.

Effects of hypersensitivity to a halothane metabolite on halothane-induced liver damage

The effect of immunologic hypersensitivity to a metabolite of halothane (trifluoroacetate) on the halothane-hypoxia-induction model was tested in mice and rats. Male Fisher 344 rats (200 g) were immunized with ovalbumin-trifluoroacetate (OVA-TFA) and the time course of the delayed hypersensitivity response determined. The animals had a peak response between 4 and 6 weeks after immunization. Rats were immunized with OVA-TFA, OVA, or saline 5 weeks before being anesthetized. Ten days before anesthesia, the animals were started on 0.1% phenobarbital in the drinking water. The animals were anesthetized with 1% halothane and 14% oxygen for 2 h. Hypersensitivity to TFA had no effect on the liver damage in either the mouse or the rat. These results do not rule out an immunologic vector in halothane hepatitis but make the involvement of TFA unlikely.

Differential peripheral nerve block by local anesthetics in the cat

Controversy still surrounds the differential susceptibility of nerve fibers to local anesthetic conduction block. In order to help resolve this controversy, we developed an in vivo model of peripheral nerve blockade in the cat that closely reproduced the clinical state. Using this model, differential rate of nerve blockade of A-alpha, A-delta, and C fibers by 2-chloroprocaine, lidocaine, bupivacaine, and etidocaine was observed and quantitated. C fibers were blocked first by 2-chloroprocaine, lidocaine and bupivacaine. Etidocaine blocked A-delta fibers first. A-alpha fibers always were blocked last. Of the four local anesthetics tested, 2-chloroprocaine produced the greatest differential rate of block of the nerve fibers, and etidocaine produced the least.

The effect on mice of practical diets containing different protein and energy levels

Mice of 2 strains were fed diets of natural ingredients in 3 different laboratories. The diets, which were fed before and after pelleting, contained levels of protein and energy within the ranges comparable to those found in existing laboratory diets and were the same formulation as those fed to rats in a previous paper. The diet with the lowest energy level supported the lowest rate of bodyweight gain, as it had with rats. Little effect was noticed on food consumption, conversion efficiency or water intake. Animals fed the pelleted diets gained bodyweight faster and there were indications of greater food and water consumption and also food conversion efficiency. It was concluded that food intake was improved with the pelleted diets resulting in the other increases.

The effect on rats of practical diets containing different protein and energy levels

Rats of 3 strains were fed diets of natural ingredients in 4 different laboratories. The diets contained different levels of protein and energy within ranges comparable to those found in existing laboratory diets. Energy level over the range examined appeared to exert greatest influence on bodyweight gain, but had no effect on food intake. The diet with the highest amino acid content was consumed in smaller amounts than the other diets. Food utilization was less efficient in the lower energy diets. Fat deposition was reduced in animals fed the lowest energy diet. It is concluded that energy level of the diet exerts an effect on the rate of bodyweight gain in rats, but that for longer-term studies a reduced energy level may be beneficial by leading to smaller fat deposits with consequent increase in longevity.

Pilot study on disposition and pain relief after i.m. administration of meperidine during the day or night

Two groups (four patients each) of sickle cell anemia patients with severe pain were studied. One group comprised patients admitted to emergency unit in the morning (5:40 to 9:15) and the other patients admitted in the evening (18:53 to 22:50). All patients received intramuscular meperidine (1.5 mg/kg). Pain intensity and pain relief were followed for 4 h; blood samples were taken up to 6 h after drug administration. Significant differences in drug disposition were found between the day and night groups, as the elimination half-life was 46% shorter during the night and the total serum clearance was 70% greater during the night. Whereas a positive correlation was found between drug concentration and pain relief for the day group, no such correlation was found for th night group. Even though peak concentrations were higher during the night, analgesia was lower. This pilot study suggests that much higher meperidine doses might be required during the night to achieve equieffective analgesia.

Genotype X diet interaction for litter size in mice

Substantial interaction was observed in 3 inbred strains of mice maintained on 5 normal commercial pelleted diets. Strain B10.BR was most sensitive to the unknown dietary factor, and the ranking of B10.BR and A2G was reversed across the array of diets. There was no apparent relationship between the ‘biological’ value of the diet and 21 dietary ingredients determined chemically. The study shows that the diet which gives the best performance for one strain of mice may not be the best for another.

Immunological properties of peptic fragments of bovine serum albumin

The effect of peptic degradation on the immunological and antigenic properties of bovine serum albumin (BSA) was investigated. Molecular fragments obtained after various times of digestion (3-360 min) were studied. Enzymatic digestion resulted in a rapid loss of serologically defined antigenic determinants. The immunogenicity of the fragments as measured by the level of reaginic and total anti-BSA antibody response in BDF1 mice was also diminished. Pre-treatment of mice with fragments exhibiting a low density of B-cell interacting determinants before immunization with BSA, resulted in significant suppression of both the primary and secondary antibody response. The most effective immunosuppressive fragments were obtained following removal of peptides which bound to anti-BSA antibodies. The suppression was shown to be antigen specific. It was concluded that separate determinants on the BSA molecule were responsible for the immunogenic and suppressive properties of the antigen.

Composition of the milk of the common marmoset (Callithrix jacchus) and milk substitutes used in hand-rearing programmes, with special reference to fatty acids

Analyses of marmoset (Callithrix jacchus) milk were carried out to determine values for crude protein, lactose, total lipids, major minerals, and osmotic pressure. Mean values were (g/100 ml): protein, 3.6; lactose, 7.5; total lipids, 7.7; minerals (mg/100 ml): sodium, 21.4; potassium, 54.3; calcium, 92.2; phosphorus, 22.8; magnesium, 5.0; chloride, 52.2; osmotic pressure, 354 mosm/kg water. Similar analyses were conducted on 2 milk substitutes used in hand-rearing programmes. Fatty acid analyses were carried out on natural milk, the milk substitutes, and the marmoset diet. For hand-rearing C. jacchus it is recommended that a human milk substitute is modified by increasing the levels of protein, carbohydrate, and total lipids, and that a small amount of fish oil is added.

Influence of diet pellet hardness and particle size on food utilization by mice, rats and hamsters

Increasing hardness of diet pellets reduced food wastage by each species. Also, less wastage occurred when pellets made from finely ground materials were given, an effect that was not related to hardness. The hardest diet reduced growth of the mice by reducing true food consumption and a poorer food conversion efficiency (true food consumption/growth) was obtained. Apparent food consumption increased with the softness of the diet and food utilization (apparent food consumption/growth) of the softest diets was less efficient than those of the others. Grinding of the raw materials prior to pelleting had no effect on food conversion, but food utilization was less efficient because of the greater wastage of pellets from coarsely ground materials and consequent apparent food comsumption.

Effect of autoclaving and physical structure of diets on their utilization by mice

A pelleted and 2 expanded rodent diets were autoclaved at 121 degrees C for 20 minutes, and fed to DBA/1 and LACA strains of mice. Reproduction was not significantly different on any diet and autoclaving had no effect other than increasing the intervals between litters. However, apparent food consumption was greater and efficiency of food utilization (expressed as young weaned/diet consumed) was poorer in mice fed pelleted diets. Diet had no significant effect on growth, but food wastage and consequently apparent food consumption were less and food utilization more efficient when expanded diets were fed. In addition, true food consumption was lower and food conversion more efficient. Autoclaving had little effect on expanded diets but caused a significant reduction in wastage and in apparent and true consumption of the pelleted diet, perhaps because of increased hardness.

The effect of methods of sterilization on the nutritive value of protein in a commercial rat diet

1. The effect on protein quality of treating a commercial rat diet by autoclaving at various temperatures for different periods of time, or by irradiation with 2-5 or 10 Mrd, was studied. True digestibility (TD) and biological value (BV) were measured and the available and total amino acids in the diets were estimated using microbiological and chemical methods. 2. Autoclaving at 121 degrees for 60 min reduced BV, TD and net protein utilization (NPU) more than autoclaving at 134 degrees for 3 min. Availability of amino acids was reduced by both treatments but to a greater extent by autoclaving at 121 degrees for 60 min. Total amino acids were essentially unaffected. Irradiation had no effect on BV, TD, NPU or total amino acids, and the availability of amino acids was also unaffected, with the exception of lysine which was slightly reduced. 3. When the diet was autoclaved at 115 or 121 degrees for 15, 30 or 60 min, or at 134 degrees for 3 min the availability of the amino acids was reduced with increasing time and temperature of treatment. Treatment at 134 degrees for 3 min had an effect on available amino acids similar to treatment at 121 degrees for 15 or 30 min. 4. Ethylene oxide fumigation of the diet caused reduced availability of histidine, methionine and tryptophan but had negligble effect on arginine, leucine and lysine. 5. It is concluded that from a practical point of view irradiation causes least damage to proteins in rodent diets. If such diets are to be autoclaved they should be supplemented with complete protein to counteract amino acid destruction.