Multicentre study of hospitalised patients with sports- and recreational cycling-related traumatic brain injury in Hong Kong

INTRODUCTION

Cycling is associated with a greater risk of traumatic brain injury (TBI) than other recreational activities. This study aimed to investigate the epidemiology of sports-related TBI in Hong Kong and to examine predictors for recreational cycling-induced intracranial haemorrhage.

METHODS

This retrospective multicentre study included patients diagnosed with sports-related TBI in public hospitals in Hong Kong from 2015 to 2019. Computed tomography scans were reviewed by an independent assessor. The primary endpoint was traumatic intracranial haemorrhage. The secondary endpoint was an unfavourable Glasgow Outcome Scale (GOS) score at discharge from hospital.

RESULTS

In total, 720 patients were hospitalised with sports-related TBI. The most common sport was cycling (59.2%). The crude incidence of cycling-related TBI was 1.1 per 100 000 population. Cyclists were more likely to exhibit intracranial haemorrhage and an unfavourable GOS score, compared with patients who had TBI because of other sports. Although 47% of cyclists had intracranial haemorrhage, only 15% wore a helmet. In multivariate analysis, significant predictors for intracranial haemorrhage were age ≥60 years, antiplatelet medication, moderate or severe TBI, and skull fracture. Among 426 cyclists, 375 (88%) had mild TBI, and helmet wearing was protective against intracranial haemorrhage, regardless of age, antiplatelet medication intake, and mechanism of injury. Of 426 cyclists, 31 (7.3%) had unfavourable outcomes on discharge from hospital.

CONCLUSIONS

The incidence of sports-related TBI is low in Hong Kong. Although cycling-related head injuries carried greater risks of intracranial haemorrhage and unfavourable outcomes compared with other sports, most cyclists experienced good recovery. Helmet wearing among recreational cyclists with mild TBI was protective against intracranial haemorrhage and skull fracture.

Transnasal penetrating intracranial injury with a chopstick

We report the first case of a transnasal penetrating intracranial injury in Hong Kong by a chopstick. A 49-year-old man attempted suicide by inserting a wooden chopstick into his left nose and then pulled it out. The chopstick caused a transnasal penetrating brain injury, confirmed by contrast magnetic resonance imaging of the brain. He was managed conservatively. Later he developed meningitis without a brain abscess and was prescribed antibiotics for 6 weeks. He enjoyed a good neurological recovery. This case illustrates that clinician should have a high index of suspicion for penetrating intracranial injury due to a nasally inserted foreign body, even though it had already been removed. In such cases moreover, brain magnetic resonance imaging is the imaging modality of choice, as it can delineate the path of penetration far better than plain computed tomography.

Angioplasty and stenting for intracranial atherosclerotic stenosis: position statement of the Hong Kong Society of Interventional and Therapeutic Neuroradiology

As a means of preventing secondary ischaemic stroke, angioplasty and stenting are considered potentially beneficial for patients with severe intracranial atherosclerotic stenosis. However, the role of stenting has been challenged since the publication of the first randomised controlled trial on Stenting versus Aggressive Medical Management for Preventing Recurrent stroke in Intracranial arterial Stenosis (SAMMPRIS). This indicated that aggressive medical management was superior to stenting using Wingspan to prevent recurrent stroke, because stenting has a high peri-procedural stroke and death rate. In this paper, we review the management of intracranial atherosclerosis, revisit the skepticism on stenting, and state our position on the topic in the form of recommendations. These are based on the prevalence of the disease in Hong Kong, the high risk of recurrent stroke despite medical therapy in the presence of haemodynamic intracranial stenosis without sufficient collaterals, an analysis of the weak points of SAMMPRIS, and results of clinical studies in Hong Kong.

Universal newborn hearing screening in Singapore: the need, implementation and challenges

With about 1 in 1000 born with severe to profound hearing loss and about 5 in 1000 with lesser degrees of loss, congenital deafness is the commonest major birth defect. It is the recommended standard that hearing loss in newborns be detected by 3 months of age and intervention implemented by 6 months of age. Delayed detection and intervention may affect speech, language and psychosocial development, resulting in poor academic achievements. Universal newborn hearing screening (UNHS) is the only effective way of detecting all babies with hearing loss, within the recommended time frame. A survey in Singapore revealed that traditional childhood hearing screening programmes resulted in late detection (mean age, 20.8 months; range, 0 to 86 months) and late intervention (mean age, 42.4 months; range, 1 to 120 months). Increasingly, UNHS is becoming standard medical care in developed countries. In Singapore, UNHS has been implemented in all hospitals with obstetric services. Although a screening rate of more than 99% has been achieved in public hospitals, private hospitals have a screening rate of only about 77%. Parents' awareness and acceptance of early detection is still lacking, and this needs to be addressed by appropriate public education. Support from obstetricians and paediatricians will significantly contribute towards this objective. Effective programme management is essential; this includes the use of data management systems, the maintenance of a team of experienced screeners, and efficient coordination between screening and diagnostic services. Early detection of childhood deafness, together with early and effective intervention, maximises the chances of successful integration into mainstream education and society.

Outcome analysis of intraventricular thrombolytic therapy for intraventricular haemorrhage

OBJECTIVES

To evaluate the outcome of intraventricular thrombolytic therapy for intraventricular haemorrhage and to formulate a safe and effective regimen.

DESIGN

Retrospective study.

SETTING

Regional neurosurgical centre, Hong Kong.

PATIENTS

Twenty-nine consecutive adult patients who presented from November 1995 to November 1998 with non-traumatic intraventricular haemorrhage (Graeb score, > or =7) with no active rebleeding risks from vascular abnormalities.

INTERVENTIONS

Fourteen consecutive patients received intraventricular streptokinase via the external ventricular drainage, and 15 consecutive patients received intraventricular urokinase treatment.

MAIN OUTCOME MEASURES

Patient demographics, Glasgow coma scale score, Graeb score, mortality rate, shunt rate, fever response, infection rate, catheter blockage rate, and local and systemic bleeding tendency.

RESULT

The mean age of the 16 men and 13 women was 59 years (range, 14-76 years). The median Graeb score for cases of intraventricular haemorrhage was 10 (range, 7-12). There was no significant difference in terms of the Graeb score distribution, total dosage, and duration of treatment between the streptokinase and urokinase groups. More cases of fever were observed in the streptokinase group, which could be due to its antigenicity. The infection rate of the central nervous system was 3%, and the shunt rate was 24%. The overall 1-month postoperative mortality was 10%, which was related to a low preoperative Glasgow coma scale score (< or =4). No local rebleeding, systemic coagulopathy, or catheter blockage occurred.

CONCLUSIONS

Intraventricular thrombolytic therapy is a safe and effective method of managing intraventricular haemorrhage. We suggest instilling 20 000 units urokinase intra-operatively, followed by 20 000 units daily for about 3 days, except in cases of vascular abnormality, bleeding tendency, and trauma.

Tuberculous meningitis with spinal tuberculous arachnoiditis

This report is of a 36-year-old woman who initially presented with confusion and fever. Subsequent investigations showed tuberculous meningitis with acute hydrocephalus. Ventriculoperitoneal shunt was performed and anti-tuberculosis therapy was given. The patient was later noticed to have weakness of both lower limbs and urinary retention. Magnetic resonance imaging of the thoracic spine showed radiological features of tuberculous arachnoiditis with cord compression. Decompressive laminectomy was performed and high-dose systemic corticosteroid was given. A high level of awareness is required when diagnosing tuberculous arachnoiditis and the importance of high-dose corticosteroid in the treatment regimen is emphasised.

Brain tuberculoma in Hong Kong

We report two cases of brain tuberculoma occurring in patients residing in Hong Kong. Both patients presented with headache and had space-occupying lesions evident on computed tomography scans of the brain. The patients had no history of tuberculosis and no symptoms of concurrent extracranial tuberculosis were evident. The diagnosis of tuberculoma was made at the time of surgical excision. Delayed diagnosis of brain tuberculoma is likely to occur in industrialised countries where tuberculosis is rare. In Hong Kong, however, with a constant influx of foreign domestic workers from endemic regions, a high index of suspicion should be maintained. Imaging studies support, but do not confirm, the diagnosis of brain tuberculoma. We recommend obtaining a definitive histological diagnosis, with computed tomography-guided stereotactic biopsy, before starting antituberculous therapy. Surgical excision is necessary in patients with raised intracranial pressure secondary to the lesion, who are not responding to medical therapy.

Odontogenic subperiosteal abscess of orbit: a case report

Subperiosteal abscess of orbit is an uncommon but serious complication of orbital infection. We report a case of a 78 year old gentleman who presented with bilateral periorbital oedema and proptosis. Computerised tomography of orbit revealed bilateral dilated superior ophthalmic veins. Bilateral carotid-cavernous fistula was initially suspected. Serial imaging showed an increasing bilateral subperiosteal lesion of the orbit. Fine needle aspiration confirmed subperiosteal abscess. A high level of awareness is necessary in diagnosing subperiosteal abscess.

Symptoms of depression in elderly Korean immigrants: narration and the healing process

This paper explores ways in which depressive symptoms are expressed by elderly Korean immigrants in the USA. Depressed elderly Korean immigrants in the Washington DC area were interviewed in depth to explore their conceptualizations of depression in terms of explanatory models and semantic networks. The expressions of depressive symptoms were influenced by linguistic and psycho-socio-cultural factors, therapeutic behaviors, and efficacy of treatment. The data were interpreted in terms of traditional Korean medical principles, cosmological, socio-cultural, and religious influences, and an individual's family structural changes and acculturation. Findings indicate the construction of somatization among Korean elders is more complex than is generally reported: in most cases, a dynamic, holistic blend of processes appears to operate simultaneously, instead of as somatization in isolation. Informants placed different degrees of emphasis on psychologization or somatization, or the two combined. The roles of personality, value orientation, intellect, emotion, economic status, degree of acculturation, degree of dependence on children, living situation (with or not with children), and self-will or self-confidence are important influences on the depression symptoms in the psychologization-somatization continuum. The more self-directed the informants are, the more they psychologize; the more other-directed, the more they seem to somatize. Names and symptoms of depression (a Western concept) and popular illnesses (traditional Korean concepts) were used interchangeably by the informants. When informants were asked to explain the signs and symptoms of depression and sadness, some described symptoms similar to the criteria of major depression in DSM-III (American Psychiatric Association), while others gave different symptoms and ways of expressing them. Some informants believed that symptoms and signs of depression can be concealed from others if one chooses to do so. Many felt that manifestations of depression can be controlled by willpower, personality, and self-care.

Prevalence of depression and somatic symptoms among Korean elderly immigrants

Forty-one Korean immigrants in Washington, D.C. (of the United States) metropolitan area over age 60 were interviewed using the Diagnostic Interview Schedule (Korean version) with additional questions about culture-specific somatic symptoms identified in previous research with Korean populations. The lifetime and current prevalence were 29.27 percent and 14.63 percent, respectively, for major depression; 9.76 percent and 2.44 percent for generalized anxiety disorder; and 9.76 percent and 7.32 percent for somatization disorder. The lifetime and current rates of co-occurrence of major depression and somatization disorder were 25 percent and 33.33 percent. Subjects who met criteria for depression were more likely to experience culture-specific Korean somatic symptoms than subjects who did not meet those criteria.

Hwabyung: the construction of a Korean popular illness among Korean elderly immigrant women in the United States

The cultural construction of Hwabyung, a Korean culture-bound syndrome, is explored among a sample of 20 elderly Korean immigrant women in the United States. Hwabyung results when distressed emotions associated with the specifically Korean way of perceiving and reacting to intolerable and tragic life situations cause bodily symptoms by interfering with the harmony of "Ki" (vital energy). Korean elderly immigrants report a broad range of symptoms associated with Hwabyung; they less frequently report the epigastric mass, which had been considered the cardinal symptom by cosmopolitan and traditional medical writers. Hwabyung is treated holistically with psychosocial support from family, spiritual comfort, home and popular remedies, traditional Korean medicine, and biomedical treatments. Hwabyung provides a way of conceptualizing and resolving emotional distress through somatization among Korean elderly immigrant women.

The practice of traditional Korean medicine in Washington, D.C

Therapeutic relationships between Korean immigrants and their hanui, traditional Korean professional physicians, and the role adaptation of these physicians in the United States are discussed. The professional practices of four hanui who work in the Washington, D.C., area are examined through case studies. Research methods included semi-structured interviews, participant observation, key informant interviews, and examination of documentary materials. In hanbang, the traditional Korean medical care system, illness is related to a disturbed state of ki, the cosmological vital energy. Symptoms are often interpreted in terms of a psychosocial base. Pathophysiology is usually illustrated in functional and holistic terms. Treatment modalities include acupuncture, herbal medicines, moxabustion, and cupping. Improvement is evaluated by the quality of pulse, the disappearance of symptoms, restoration of the appetite and of a healthy look and voice, and the return of the ability to function in everyday life. The therapeutic relationship between hanui and their clients is genuine, spontaneous, and harmonious. Clients actively enter into the clinical process by negotiating with hanui about treatment decisions. Hanui practicing in the United States modify their practices to meet their immigrant clients' expectations in relation to the impact of Western biomedicine. They may use some biomedical diagnostic techniques, offer traditional medicines in tablet form, and explain symptoms and treatment with reference to some biomedical terms. Koreans use both hanbang and Western biomedical treatments. However, clients who receive both types of therapy may experience conflicts because of the lack of cooperation between hanui and biomedical physicians.

Structural and functional maturation of rat gastrointestinal barrier with thyroxine

It has been noted that the closure of the intestinal barrier to immunoglobulins is a normal maturational process in the rat. It has also been noted that the microvillus membrane (MVM) of newborn animals differs from adult MVM. The purpose of this study is to document whether thyroid hormone can induce closure in vivo in the rat and to relate this effect of thyroxine to the structural and functional maturation of the intestinal MVM. To assess closure, 2-wk-old rats were fed a rat immunoglobulin G (IgG), and serum antibody binding activity was measured 4 h later. The antibody binding activity of treated animals (T) was 1.5-2 times less than that of controls (C) (P less than 0.001), indicating that thyroxine stimulates closure. The MVM similarly showed signs of maturation. Structural maturation was demonstrated by the lower fluidity of the thyroid-treated animals' membranes. Under the influence of thyroxine, the number of receptors on the MVM for IgG had decreased [2.8 X 10(-7) M (C) vs. 1.7 X 10(-7) M (T)], while the Ka remained the same, demonstrating the functional maturation of the MVM. In conclusion, thyroid hormone can induce both structural and functional maturation of the intestinal MVM and can enhance the intestinal mucosal barrier by decreasing the penetration of antibodies.

Development of gastrointestinal surface. VIII. Lectin identification of carbohydrate differences

Binding of microvillus membranes (MVM) from newborn and adult rats by concanavalin A (Con A), Ulex europaeus (UEA I), Dolichos bifluorus (DBA), and Triticum vulgaris (WGA) was examined to determine the availability of carbohydrate-containing sites for these lectins on the intestinal surface during development. Consistent patterns of differences in the reaction of MVM with these lectins were found. Con A and UEA had much higher reactivities to MVM of adult than newborn rats. 125I-labeled-UEA gel overlay experiments revealed the abundance of UEA-binding sites in MVM of adult rat in contrast to the two binding sites in MVM of a newborn rat. DBA bound only to MVM of the adults, and very few binding sites were found in immature MVM. In contrast to these lectins, WGA binding was much higher in MVM of the newborns and decreased with maturation. Additional experiments on the age dependence of UEA and DBA reactivities revealed that the most striking changes occur in animals from 2 to 4 wk of age. In MVM from 2-wk-old rats, there were only 13.9% and less than 0.2% of the adult binding capacities for UEA and DBA, respectively. By the time the animals were 4 wk old, the binding capacity for UEA had attained close to the level of the adults, whereas for DBA it reached 71.3% of the adult value. These results provide definite evidence of changes in the intestinal surface during perinatal development.

The effect of short-term starvation on mucosal barrier function in the newborn rabbit

The compromised human newborn frequently presents with overwhelming feeding problems which lead to inadequate intake. These problems may affect the development of the small intestine, especially mucosal barrier function, leading to increased infections and susceptibility to allergens. To study this, an animal model was established using neonatal rabbits deprived of nutrients from birth until 72 h. Mucosal barrier function was compared in deprived and control (naturally fed 72-h-old animals) rabbits by measuring immunoreactive bovine serum albumin in serum 4 h after intragastric infusion of crystalline bovine serum albumin (200 mg/100 g body weight). Trypsin activity was measured in rinse fluid obtained from the small intestine. Representative sections of jejunum from control and experimental animals were formalin fixed and stained with hematoxylin and eosin for morphologic comparison. Following the bovine serum albumin feeding, a significantly increased serum immunoreactive bovine serum albumin and significantly decreased trypsin-like activity of the small intestinal rinse fluid was noted in starved animals compared to controls. In addition, the enterocytes of malnourished animals were more cuboidal and contained fewer and smaller supranuclear granules on microscopic examination than the enterocytes of controls. This study suggests that short-term starvation in newborns affects mucosal barrier function. Acute starvation may place newborns at increased risk for infections and allergic disease.

Development of gastrointestinal mucosal barrier. VII. In utero maturation of microvillus surface by cortisone

When studying mucosal barrier function of developing animals, we noted that intestinal microvillus membranes (MVM) of newborn animals differ in their fluidity and binding characteristics to lectins compared with adult MVM. To further investigate these differences and determine whether maturation of the microvillus surface could be accelerated in utero, pregnant rats were given intraperitoneal cortisone beginning on the 17th day of gestation. Control and cortisone-treated animals were allowed to deliver normally, and the small intestines from newborns were used to isolate MVM. Microvillus membrane surface characteristics were evaluated by employing an 125I-labeled fucose-specific lectin, Ulex europeus (UEA). Changes in MVM proteins were monitored by disaccharidase activities and sodium dodecyl sulfate-polyacrylamide electrophoresis. MVM fluidity was accessed using a 5-doxyl stearic acid label and electron-spin-resonance spectroscopy. Results from these studies indicate that the birth weights of newborn rats exposed to cortisone in utero were significantly reduced; sucrase activity was prematurely induced and specific activities of lactase and maltase were enhanced in the intestines of the cortisone-treated newborns as contrasted with control animals. Furthermore, binding of 125I-UEA to MVM was greatly increased in treated animals. MVM fluidity decreased (P less than 0.001) compared with control animals and resembled the structural characteristics of more mature MVM. These results suggest that cortisone exposure in utero accelerate maturation of the microvillus surface of enterocytes.

Food proteins and gut mucosal barrier. II. Differential interaction of cow's milk proteins with the mucous coat and the surface membrane of adult and immature rat jejunum

Two in vitro intestinal models were used to investigate postnatal maturational changes of the gut barrier functions. Microvillus membrane (MVM) preparations were studied for surface binding, and everted gut sacs were studied for mucous coat binding, breakdown and uptake of radioiodinated bovine serum albumin (BSA), and beta-lactoglobulin (beta-LG). Surface binding of these proteins to MVM was weak and nonspecific. There was more binding of both proteins to immature MVM (BSA: newborns, 2.74 +/- 0.52%, adults, 1.08 +/- 0.17%, p less than 0.001; beta-LG: newborns, 6.30 +/- 0.54%; adults, 2.05 +/- 0.07, p less than 0.001). In contrast to MVM binding characteristics, mucous coat binding of the cow's milk proteins to immature gut sacs was significantly less (BSA: preweanlings, 0.94 +/- 0.30 micrograms 125-I-protein Eq/mg mucosal protein; adults, 3.06 +/- 0.74, p less than 0.001; beta-LG: preweanlings, 5.61 +/- 1.48; adults, 9.83 +/- 1.33, p less than 0.001). Protein binding and uptake were correlated in the immature animals (r = 0.76, p less than 0.001 for BSA and r = 0.85, p less than 0.001 for beta-LG). More beta-LG was bound and taken up than BSA in the preweanlings (p less than 0.001). Trichloroacetic acid precipitation studies showed that, even in the immature rats, beta-LG was much more readily broken down by mucosa-associated enzymes than BSA. Immature animals showed less protein breakdown than adult controls. Decreased protein breakdown and mucous coat binding as well as increased MVM binding may account for the increased uptake of intact food antigens in the newborn.(ABSTRACT TRUNCATED AT 250 WORDS)

Microvillus membrane differentiation: quantitative difference in cholera toxin binding to the intestinal surface of newborn and adult rabbits

Microvillus membranes (MVM) were isolated from newborn and adult New Zealand rabbit small intestine. The isolation procedure provided a mean enrichment of 25 +/- 4 for sucrase activity in adult preparations and of 27 +/- 3 for lactase activity in newborn preparations. These purified MVM were incubated with increasing concentrations of 125I-labeled cholera toxin (CT). 125I-CT binding to adult MVM reached saturation at 6.4 X 10(-9) M; in contrast 125I-CT binding to newborn MVM did not reach saturation but instead continued to increase with increasing 125I-CT concentrations. Scatchard plot analysis of adult data supported the existence of a single binding site (Kd = 1.2 +/- 0.2 X 10(-9) M); analysis of newborn data, however, suggested the existence of additional binding sites, as 125I-CT binding to newborn MVM was inhibited by preincubation with unlabeled CT. These results show that CT binding to both preparations is quantitatively different and is higher in newborn preparations. This difference may be accounted for by the existence of additional binding sites in newborn MVM preparations in contrast to the presence of only the unique receptor previously reported in adult MVM preparations.

Development of the gastrointestinal mucosal barrier V. Comparative effect of calcium binding on microvillus membrane structure in newborn and adult rats

Electron spin resonance (ESR) and the spin label method, with 5-doxyl stearic acid as a probe, were used to investigate the structure of microvillus membrane (MVM) from small intestine of adult and newborn rats. It was shown that the spin label in MVM of newborn was maintained in a more disordered environment than the spin label in adult animals. Calcium ion was used as an external stimulus to study the structural response and organization of these two membrane preparations. Ca++ enhanced the order of 5-doxyl stearic acid labeled MVM from mature and immature rats in a concentration-dependent saturable process, but Ca++ exerted a greater ordering effect on MVM from immature than MVM from the mature rat. Ca++ binding to MVM was also a concentration-dependent, saturable process. MVM from immature rat bound significantly more Ca++ in CaCl2 concentration ranges from 12.5 micron to 4mM. Scatchard analysis of the binding data showed two classes of binding sites with a high affinity constant of 3.1 X 10(4) M-1 and a low affinity constant of 9.1 X 10(3) M-1, with corresponding maximum binding capacities for each class site of 129.8 nmole of calcium/mg protein and 252.7 nmole calcium/mg of protein in newborn and 13-day-old MVM. Only one high affinity constant of 2.6 X 10(4)M-1 with a corresponding maximum binding capacity of 106.4 nmole/mg of protein was observed in adult MVM. Proteolytic hydrolysis of the membranes by trypsin produced an increase in Ca++ binding in adult MVM and a decrease in Ca++ binding in newborn MVM. Neuraminidase and phospholipase C reduced the amount of bound Ca++ in both adult and newborn MVM. These results indicate a more disordered structure of newborn MVM and a differential effect of Ca++ on MVM during development.

Age-related changes in chemical composition and physical properties of mucus glycoproteins from rat small intestine

Mucus glycoproteins from newborn and adult rat small intestine were radiolabelled in vivo with Na2 35SO4 and isolated from mucosal homogenates by using Sepharose 4B column chromatography followed by CsCl-density-gradient centrifugation. Non-covalently bound proteins, lipids and nucleic acids were not detected in the purified glycoproteins. Amino acid, carbohydrate and sulphate compositions were similar to chemical compositions reported for other intestinal mucus glycoproteins, as were sedimentation properties. There were, however, important differences in the chemical and physical characteristics of the mucus glycoproteins from newborn and adult animals. The buoyant density in CsCl was higher for the glycoproteins from newborn rats (1.55 g/ml versus 1.47 g/ml). On sodium dodecyl sulphate/polyacrylamide/agarose-gel electrophoresis, the glycoprotein from newborn rats had a greater mobility than the adult-rat sample. Although both preparations had similar general amino acid compositions, variations were observed for individual amino acids. The total protein content was greater in the glycoprotein from newborn animals (27%, w/w, versus 18%, w/w). The molar ratio of carbohydrate to protein was less in the newborn, primarily owing to a decreased fucose and N-acetylgalactosamine content. Comparison of the molar ratio of fucose and sialic acid to galactose for both glycoproteins demonstrated a reciprocal relationship similar to that described by Dische [(1963) Ann. N.Y. Acad. Sci. 106, 259-270]. The sulphate content was greater in the glycoprotein from newborn rats (5.5%, w/w, versus 0.9%, w/w). Both had similar sedimentation coefficients in a dissociative solvent. These results suggest an age-related difference in the types of mucus glycoproteins synthesized by small intestine.

Development of the gastrointestinal mucosal barrier. Evidence for structural differences in microvillus membranes from newborn and adult rabbits

Electron spin resonance (ESR) and spin label methods with 5-doxylstearic acid as a probe were used to investigate the structure of microvillus membrane from the small intestine of adult and newborn rabbits. The spin label in microvillus membrane of newborns appeared to be in a more disordered environment than spin label in microvillus membrane of adult animals in the temperature range from 4 to 56 degrees C. In addition, a temperature transition at 39.6 +/- 0.3 degrees C was observed in the temperature dependence of the hyperfine splitting parameter for microvillus membrane from adult animals whereas a linear temperature dependence of the hyperfine splitting parameter was found for microvillus membrane from newborns. Cholera toxin was used as an external stimulus to test for the structural response in these two membrane preparations. Cholera toxin at 6 pM caused a decrease in the hyperfine splitting parameter at temperatures below 40 degrees C and a shift in the temperature break from 39.6 degrees C to 30.7 degrees C in microvillus membrane from adults. Using microvillus membrane from newborns, the temperature dependence of the hyperfine splitting parameter remained linear with a cholera toxin stimulus and the disordering effect of cholera toxin was only observed below 30 degrees C. These studies suggested that microvillus membrane from newborns were inherently more disordered than microvillus membrane from adult animals and that this difference in membrane organization might in part account for the increased attachment and penetration of macromolecules noted during the perinatal period.

Intestinal uptake of macromolecules. Differences in distribution and degradation of protein antigen in control and immunised rats

The present study examined intraluminal events in the in vivo processing of a protein antigen by the intestine of normal and orally immunised rats. One hour after the administration of 125I-bovine serum albumin (125I-BSA) and unlabelled BSA by gavage, the majority of the radioactivity was found in the distal small intestine of control and immunised rats but there was a difference in the distribution of radioactivity. In contrast with controls, immunised rats retained a lesser percentage of radioactivity in the proximal small intestine and a greater percentage of radioactivity in the distal small intestine. Radioactive substances present in intestinal rinse fluids and mucosal extracts were characterised by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), density gradient ultracentrifugation, and by immunochemical methods. Rinse fluids and mucosal extracts from immunised rats fed 125I-BSA by gavage contained high molecular weight components with characteristics of antigen-antibody complexes. Rinse fluids and extracts of normal rats contained more intact BSA and less fragments of BSA than did rinse fluids and extracts from immunised animals. These findings suggest that oral immunisation alters the distribution of antigen administered into the gut and that immunisation enhances the intraluminal degradation of antigen.