The cardiovascular responses of male subjects to kung fu techniques. Expert/novice paradigm

BACKGROUND

The primary aim was to assess cardiovascular responses of expert and novice subjects to kung fu techniques. It was hypothesised that experienced subjects would demonstrate improved economy of movement during the techniques, evidenced by reduced exercise intensity.

METHODS

EXPERIMENTAL DESIGN

a comparative design was established utilising two groups; experienced (group E), and novice (group N).

SETTING

the experimentation took place under laboratory conditions, but was designed to maximise external validity.

PARTICIPANTS

the only preselection variables were regular attendance at training and experience. Nine experienced males (group E, exp 9.5 +/- 5.2 yrs) and nine novice males (group N, exp 1.2 +/- 0.1 yrs) participated. The only exclusion guidelines were contraindications to participate within a maximal test, no subjects were excluded upon this basis.

INTERVENTIONS

N/A.

MEASURES

each subject participated in three kung fu protocols (forms, kicking and punching). Each protocol, randomly allocated, consisted of ten work (30 sec) and ten rest periods (30 sec). MEASURES taken during the protocols were heart rate (HR) and oxygen consumption (VO2). These were expressed as a percentage of maximal values to reflect exercise intensity.

RESULTS

During both the form protocol and punching protocol group E were found to be working at a significantly (p < 0.05) lower % VO2 max than group N (forms--group E = 71.5 +/- 5.3, group N = 82.1 +/- 6.1; punching--group E = 37.5 +/- 2.1, group N = 40.6 +/- 2.6, p < 0.05). This suggests that experienced subjects were more economical when performing similar movement patterns.

CONCLUSIONS

It was concluded that cardiovascular responses to kung fu techniques differ depending upon experience level. It is difficult to directly relate this to improved economy since work output could not be accurately quantified. It was also found that kung fu protocols elicited exercise intensity into the cardiovascular training zone.

Secreted effector proteins of Salmonella dublin act in concert to induce enteritis

The ability of enteropathogenic salmonellae to recruit inflammatory cells and induce secretory responses in the infected ileum is considered to be a main feature in Salmonella-induced enteritis. Interactions between the pathogen and intestinal epithelial cells result in a variety of cellular responses mediating inflammation and fluid secretion. It is becoming apparent that proteins secreted by the Inv-Spa type III secretion system of Salmonella spp. play a key role in the induction of these responses. We have recently demonstrated that the SopB effector protein is translocated into eukaryotic cells via a Sip-dependent pathway and mediates inflammation and fluid secretion in infected ileal mucosa. However, SopB did not appear to be the only effector involved, as inactivation of the sopB gene only partially impaired enteropathogenicity. We suggested that at least some of such protein effectors are likely to be proteins of the same class as SopB, i.e., secreted effector proteins translocated into eukaroyotic cells via a Sip-dependent pathway. In this work, we identify SopD, another secreted protein belonging to the family of Sop effectors of Salmonella dublin. Using the cya reporter system we showed that SopD is translocated into eukaroyotic cells. We assessed the potential involvement of SopD in enteropathogenicity and found that inactivation of sopD has an additive effect in relation to the sopB mutation.

Identification of a pathogenicity island required for Salmonella enteropathogenicity

Salmonella spp. interact with ileal mucosa and disrupt normal intestinal function, which results in an acute inflammatory cell influx, fluid secretion and enteritis. We have recently characterized SopB, a novel secreted effector protein of Salmonella dublin, and presented evidence that SopB is translocated into eukaryotic cells via a sip-dependent pathway to promote fluid secretion and inflammatory responses. Here, we show that sopB is located on a large DNA fragment unique to the Salmonella chromosome. This locus is conserved in Salmonella and maps at approximately 20 centisome of the S. typhimurium chromosome. Sequence analysis revealed that this Salmonella-specific DNA fragment is flanked by DNA sequences with significant sequence similarity to the Escherichia coli K-12 genes, tRNA1ser (serT) on one side and copS/copR on the other. Thus, this Salmonella-specific DNA fragment has features characteristic of 'pathogenicity islands' and, therefore, it was denoted SPI-5 (Salmonella pathogenicity island-5). SPI-5 was sequenced and was found to contain five novel genes, pipA, pipB, pipC, pipD (pathogenicity island-encoded proteins) and orf, in addition to sopB. The effect of mutations in pipA, pipB and pipD on the induction of fluid secretion and an acute inflammatory cell influx was assessed in bovine ligated ileal loops. The effect of mutations in SPI-5-encoded genes on systemic salmonellosis was assessed in mice. The results of these experiments suggest that SPI-5-encoded genes contribute to enteric but not to systemic salmonellosis.

Development and validation of the Impulse Buying Tendency Scale

Previous research suggests that individuals vary in their proclivity to purchase products on impulse. This paper presents the results of four studies (Study 1, n = 212; Study 2, n = 152; Study 3, n = 124; and Study 4, n = 550) designed to develop and validate the Impulse Buying Tendency Scale. Data from the first three studies indicate that the scale is unidimensional and internally consistent. The third study provides evidence supporting convergent validity and discriminant validity and the fourth of predictive validity.

Longterm mortality outcome in patients with rheumatoid arthritis: early presenters continue to do well

OBJECTIVE

Patients with rheumatoid arthritis (RA) have reduced life expectancy; however, there are few data on the changing pattern of causes of death with longterm followup, or on the longterm effect of early presentation. The objectives of this study were (1) to examine the effect of early presentation on subsequent mortality; (2) to compare the causes of death early and late in the followup period; and (3) to compare survival of the cohort with that of the general population (adjusted for age and sex) over a followup period of up to 27 years.

METHODS

A cohort of 448 patients with RA (inpatients and outpatients), assembled 1968-74, were followed to December 31, 1990. Death certificates were obtained for all who had died and coded using the International Classification of Diseases. Kaplan-Meier survival curves were constructed.

RESULTS

By the end of the study, 266 patients (59%) had died. The standardized mortality ratio (SMR) was 2.7 (95% CI 2.4-3.1). Patients who presented early continued to do well. Most excess deaths were due to cardiovascular disease. SMR due to infection, renal failure, and non-Hodgkin's lymphoma rose with disease duration.

CONCLUSION

Patients with RA should be referred early, and those with chronic disease should be closely monitored for evidence of infection and renal impairment.

The biosynthetic pathway of vitamin C in higher plants

Vitamin C (L-ascorbic acid) has important antioxidant and metabolic functions in both plants and animals, but humans, and a few other animal species, have lost the capacity to synthesize it. Plant-derived ascorbate is thus the major source of vitamin C in the human diet. Although the biosynthetic pathway of L-ascorbic acid in animals is well understood, the plant pathway has remained unknown-one of the few primary plant metabolic pathways for which this is the case. L-ascorbate is abundant in plants (found at concentrations of 1-5 mM in leaves and 25 mM in chloroplasts) and may have roles in photosynthesis and transmembrane electron transport. We found that D-mannose and L-galactose are efficient precursors for ascorbate synthesis and are interconverted by GDP-D-mannose-3,5-epimerase. We have identified an enzyme in pea and Arabidopsis thaliana, L-galactose dehydrogenase, that catalyses oxidation of L-galactose to L-galactono-1,4-lactone. We propose an ascorbate biosynthesis pathway involving GDP-D-mannose, GDP-L-galactose, L-galactose and L-galactono-1,4-lactone, and have synthesized ascorbate from GDP-D-mannose by way of these intermediates in vitro. The definition of this biosynthetic pathway should allow engineering of plants for increased ascorbate production, thus increasing their nutritional value and stress tolerance.

Peptidergic innervation of the rat cornea

Corneal nerves regulate corneal epithelial integrity, proliferation, and wound healing. The mechanisms by which the nerves mediate their effects remain poorly understood; however, the release of biologically active neuropeptides has been hypothesized. The purpose of the current investigation was to determine the relative densities, distribution patterns, and origins of rat corneal nerves containing each of eight different neuropeptides, calcitonin gene-related peptide (CGRP), substance P (SP), galanin (GAL), neuropeptide Y (NPY), methionine-enkephalin (M-ENK), vasoactive intestinal polypeptide (VIP), somatostatin (SOM), and cholecystokinin (CCK). In the first set of experiments, immunohistochemical demonstrations of the above neuropeptides were performed on free-floating corneal sections cut tangential to the corneal surface. The results showed that six of the peptides, CGRP, SP, GAL, NPY, M-ENK, and VIP were present in rat corneal nerves. The innervation patterns of corneal nerves containing each of these six peptides were then documented by mapping all fibers in serial sections from select corneal quadrants onto a series of line drawings by using a drawing tube. In the second set of experiments, the origins of the corneal peptidergic nerve fibers were determined by selective ocular denervations. Unilateral combined sensory and sympathetic ocular denervations or unilateral sympathetic ocular denervations were performed in adult rats by transecting the ophthalmomaxillary nerve and/or removing the superior cervical ganglion. After 5-7 days, each of the ipsilateral corneas was sectioned and processed immunohistochemically for the presence of one of the six peptides found in experiment one, and the fibers that survived the ocular denervations were plotted onto line drawings. Ocular denervations revealed that corneal peptidergic nerves have sensory (CGRP, SP, and GAL), sympathetic (NPY), and parasympathetic (GAL, NPY, M-ENK, and VIP) origins. The results of this investigation have shown that the peptidergic innervation of the rat cornea is more extensive and complex than previously reported. This is the first investigation to show the presence of GAL in the rat cornea, and the first to demonstrate the presence of NPY-, VIP-, and M-ENK-IR nerve fibers in the cornea of any species.

Parasympathetic innervation of the rat cornea

The mammalian cornea receives a dense sensory innervation and a modest sympathetic innervation. The purpose of the current study was to determine if the rat cornea is also innervated by parasympathetic nerves. In the first set of experiments, unilateral combined sympathetic and sensory ocular denervations were performed in adult rats by surgical removal of the superior cervical ganglion and intracranial transection of the trigeminal ophthalmomaxillary nerve. Completeness of the denervation procedure was verified postmortem by a variety of macroscopic and immunohistochemical methods. Five to twelve days later, the corneas were serially sectioned tangential to the ocular surface and processed immunohistochemically with antibodies against the pan-neuronal markers, protein gene product 9.5 (PGP-9.5) and peripherin. In every animal a small, but constant, population of corneal and limbal immunoreactive fibers were unaffected by the surgical denervations and were concluded to derive from parasympathetic ganglia. In the second set of experiments, the origins of the rat corneal innervation were determined by applying the neuroanatomical tracer, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) to the central cornea. Two to four days later, the trigeminal, superior cervical, ciliary, accessory ciliary and pterygopalatine ganglia were sectioned and analysed for the presence of HRP-labeled neurons. Examination of the corneal application site and associated ocular tissues revealed no evidence of tracer spread into neighbouring structures. Small numbers (0-6 per animal) of HRP-labeled neurons were observed in the ipsilateral ciliary and accessory ciliary ganglia of most animals. The results of these carefully controlled studies provide strong anatomical evidence of a modest parasympathetic innervation of the rat cornea.

Pelvic retroperitoneal schwannoma mimicking an ovarian neoplasm: report of a case and review of the literature

A pelvic retroperitoneal schwannoma that was initially thought to be an ovarian neoplasm is reported. The clinicopathologic features of this rare tumor are presented and the literature is reviewed.

Adenocarcinoma of the epididymis: a report of four cases and review of the literature

Primary epididymal carcinoma is extremely rare and has been the subject of only sporadic case reports; the validity of some of the reported tumors is questionable. We report our experience with four examples, which arose in men 27, 66, 77, and 81 years of age. All of them presented with scrotal masses; three of them had small hydroceles. None had a history of von Hippel-Lindau disease. Grossly, all of the tumors were centered in the epididymis and two were confined to it. One tumor invaded the periepididymal soft tissue and spermatic cord and the fourth invaded the adjacent testis. They were 2.0-7.0 cm in greatest diameter; three had foci of hemorrhage and necrosis. Microscopically, all of the tumors were adenocarcinomas. Two of them were composed of approximately equal numbers of simple tubules and more complex tubulopapillary formations lined by cuboidal or columnar predominantly clear cells that infiltrated the epididymal smooth muscle wall, periepididymal soft tissue, or both. The other two had large cysts into which grew complex papillary or confluent, back-to-back glands lined by columnar cells with clear, lightly amphophilic or eosinophilic cytoplasm. Necrosis was present in three cases. An undifferentiated, sheetlike growth of anaplastic tumor cells was present focally in one case. Cilia were absent. Small amounts of cytoplasmic glycogen were present in the two cases in which periodic acid-Schiff staining was performed. Immunohistochemical staining, performed in one case, demonstrated strong positivity for cytokeratins (AE1/3, Cam 5.2) and epithelial membrane antigen (luminal only). Results of staining for carcinoembryonic antigen, Leu M1, B72.3, and Ber-EP4 were negative. Ultrastructural analysis, performed in one case, showed well-developed desmosomal junctions, cytoplasmic multivesicular bodies, glycogen particles, and well-developed cilia. Two of three patients with follow-up data died of disease 8 months and 2.5 years after diagnosis; the third was disease free 30 years after the diagnosis despite having paraaortic lymph node metastases at the time of presentation. After reviewing the literature and analyzing our cases, we conclude that bona fide examples of epididymal adenocarcinoma are usually tubular, tubulocystic, or tubulopapillary adenocarcinomas, often with an appreciable content of clear cells, which can usually be readily separated from other paratesticular malignant tumors, such as malignant mesothelioma and carcinomas of the müllerian type. Distinction from metastasis may be difficult and may depend largely on careful clinical evaluation.

Atypical oxyphilic metaplasia of the endocervical epithelium: a report of six cases

We report six examples of a hitherto undescribed atypical metaplastic change of endocervical glandular epithelium that we have designated atypical oxyphilic metaplasia of the endocervical epithelium. The patients ranged in age from 41 to 62 (mean 47.8) years; one was postmenopausal. Gravidity ranged from one to five (mean 2.8) and parity from one to four (mean 2.7). At the time of diagnosis one patient was taking combined oral contraceptives and one was taking tamoxifen for breast cancer. All of the lesions were incidental findings and were unassociated with a gross abnormality. Microscopically, affected endocervical glands were lined by large cuboidal or polygonal epithelial cells with dense, eosinophilic, focally vacuolated cytoplasm and varying degrees of nuclear atypia. Nuclei were enlarged, hyperchromatic, and frequently multilobated or multinucleated. Rare apical snouts were present in two cases. Stratification and mitotic activity were absent. Rare, focal periodic acid-Schiff positivity with and without diastase predigestion was present in three of three cases. Mucin staining was negative in two of three cases and focally stained luminal secretions in one of three cases. Three of three cases were negative for GCDFP-15 and carcinoembryonic antigen. Meaningful follow-up in four patients ranged from 1 to 15 (mean 5.5) years and was uneventful in all of them. Atypical oxyphilic metaplasia of endocervical epithelium represents yet another benign endocervical glandular atypia that must be distinguished from more serious lesions.

Benign fibromatous tumors of the testis and paratesticular region: a report of 9 cases with a proposed classification of fibromatous tumors and tumor-like lesions

Benign intrascrotal fibrous proliferations are uncommon, with most arising from the paratesticular region and falling into the category of so-called fibrous pseudotumor. We describe two neoplastic forms of benign fibrous tumor of the testis and its adnexa: fibroma of gonadal stromal origin and fibroma of the testicular tunics. Three patients with gonadal stromal fibroma were 28, 33, and 35 years of age and presented with painless masses. The tumors were circumscribed, intratesticular, yellow-white or white lesions 0.9 to 4.0 cm in diameter and had microscopic features identical to those of the ovarian fibroma. Immunohistochemically, the tumor cells were strongly positive for vimentin (3/3 cases), focally positive for actin and desmin (2/3 cases) and negative for S-100, keratin, and CD34 (3/3 cases). Six fibromas of the testicular tunics arose in patients 22, 34, 60, 68, 70, and 74 years old and were also asymptomatic masses. Four of them were circumscribed, whorled, white masses arising from the tunica albuginea with variable areas of myxoid change; one was pedunculated and grew exclusively into the cavity of the tunica vaginalis, whereas the other three at least partially extended into the testis as well. The other two tumors were unattached to the tunica albuginea and presented as circumscribed, white-tan paratesticular masses, partially covered by tunica vaginalis. Microscopically, the tumors were slightly to moderately cellular, with bland spindle or stellate cells lying in a myxoid or collagenous stroma with prominent vessels. The two paratesticular tumors had features typical of solitary fibrous tumor. Immunohistochemically, the fibromas of the testicular tunics were negative for S-100, keratin, and desmin. Focal, weak reactivity for actin was present in one case. CD34 was positive in three cases; in the two tumors resembling solitary fibrous tumors it was strong, and in the other it was focal and was limited to the region just below the tunica vaginalis. Eight tumors were treated by radical orchiectomy and one by excision of the mass alone. The outcome was benign in the seven cases in which followup information is available.

Effect of covalent modification on coproporphyrinogen oxidase from chicken red blood cells

The biosynthesis of heme is a complex multi-step pathway requiring the efforts of eight enzymes. The initial enzymes in the heme biosynthetic pathway have been well characterized in relation to their mechanisms. Coproporphyrinogen oxidase (Copro'gen oxidase) is one of the last three enzymes in the pathway and is one of the least well understood. Copro'gen oxidase converts coproporphyrinogen III to protoporphyrinogen IX via oxidative decarboxylation of the 3- and 8-propionic side chain moieties. To further our understanding of the recognition and binding of substrate, Copro'gen oxidase was partially purified from chicken red blood cell hemolysates then incubated with covalent modifiers of specific amino acids. Incubation with tetranitromethane, p-hydroxyphenylglyoxal, N-acetylimidazole, or trinitrobenzenesulfonic acid resulted in substantial reduction of Copro'gen oxidase activity implying the presence of critical tyrosine, arginine and lysine residues. We conclude that these amino acids play important roles in the enzymic mechanism (for both binding and catalysis) of Copro'gen oxidase.

Sympathetic stimulation of corneal epithelial proliferation in wounded and nonwounded rat eyes

PURPOSE

To determine the effect of ocular sympathetic nerves on corneal epithelial proliferation in the rat.

METHODS

Osmotic pumps filled with bromodeoxyuridine (BrdU) were implanted subcutaneously in adult rats to label corneal epithelial cells entering the S-phase of the cell cycle during a 24-hour period. Corneas in some animals were wounded with n-heptanol. Several days or weeks before pump implantation, animals were subjected to either unilateral superior cervical ganglionectomy (SCGectomy), unilateral transection of the cervical sympathetic trunk (sympathetic decentralization), bilateral SCGectomy plus unilateral topical norepinephrine administration, or unilateral SCGectomy plus systemic capsaicin administration. Differences in BrdU-labeling indices between experimental and control eyes in each group were determined from cell counts on paraffin sections.

RESULTS

Superior cervical ganglionectomy and sympathetic decentralization significantly decreased epithelial proliferation in nonwounded and wounded corneas. Topical applications of norepinephrine to eyes that had been deprived of their sympathetic innervation completely reversed the antiproliferative effect of ocular sympathectomy. Systemic administration of the neurotoxin capsaicin, in conjunction with unilateral SCGectomy, did not alter the proliferative rate; comparison was made to animals that received unilateral SCGectomy only.

CONCLUSIONS

Ocular sympathetic nerves stimulate rat corneal epithelial proliferation under normal physiological conditions and during corneal wound healing. The promotion of DNA synthesis by these nerves occurs independently of functional interactions with capsaicin-sensitive, ocular sensory nerves and appears to be related, at least in part, to the release of norepinephrine.

Endocervical type A (noncystic) tunnel clusters with cytologic atypia. A report of 14 cases

Tunnel clusters (TCs) are benign, pseudoneoplastic glandular lesions of the cervix that may be divided into type A (noncystic) and type B (cystic). We report 14 examples of type A TC characterized by a florid proliferation of glands with greater cytologic atypia than normally encountered in this lesion. The majority had been sent for consultation to exclude adenoma malignum (minimal deviation adenocarcinoma). The patients ranged in age from 32 to 54 (mean 44.8) years. Mean gravidity was 2.5 and parity 2.1; all but one patient were multigravid. A history of recent exogenous hormone intake was present in 4 (33%) patients. All of the lesions were incidental findings, and none was associated with a gross abnormality. Microscopically, all were characterized by a lobulated proliferation of predominantly small-caliber, nondilated, closely packed glands frequently arranged around a central primary or secondary endocervical cleft. Most were well circumscribed, but irregular borders created a pseudoinvasive appearance in four cases. The lesions ranged from 2.5 to 7 (mean 3.5 mm) and were frequently associated with type B TC. The glands were lined by either mucinous columnar cells or low cuboidal cells. Cellular crowding with pseudostratification was common, but true stratification or cribriforming was absent. All cases had foci of cytologic atypia including nuclear enlargement, hyperchromasia, prominent nucleoli, and vesicular chromatin. Mitotic activity was absent or inconspicuous. Follow-up in 9 patients (7 treated with hysterectomy, one each with cone biopsy and biopsy only) ranged from 1 to 6 (mean 2.7) years and was uneventful in all of them. Follow-up was unavailable in one, and four were recent cases. Endocervical type A TC with cytologic atypia is a common benign glandular lesion that must be distinguished from adenoma malignum.

Comparative metabolism of Mesoplasma, Entomoplasma, Mycoplasma, and Acholeplasma

Cytoplasmic fractions from species of the Mollicutes genera Entomoplasma, Mesoplasma, Mycoplasma, and Acholeplasma were assayed for NADH oxidase (NADH ox), ATP- and PPi-dependent phosphofructokinase (PFK), ATP- and PPi-dependent deoxyguanosine kinase (dGUOK), thymidine kinase (TK), TMP kinase (TMPK), glucose-6-phosphate dehydrogenase (G6Pde), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), phosphoenolpyruvate carboxylase, hypoxanthine-guanine phosphoribosyl transferase, dUTPase, and uracil-DNA glycosylase (UNG) activities. Membrane fractions were also examined for NADH ox activity. These activities were used as indicators of the presence and relative activities of major Mollicutes metabolic and DNA repair pathways. This was the first study to determine the presence of these enzymes in members of the genera Entomoplasma and Mesoplasma. Using the data obtained, we constructed a preliminary scheme for distinguishing genera of the class Mollicutes on the basis of the results of signature functional enzyme assays. This scheme includes phylogenetic relationships deduced from rRNA analyses, but is more informative with respect to metabolic potential. The criteria used include the presence of PPi-dependent PFK, urease, dUTPase, and dGUOK activities. Entomoplasma ellychniae ELCN-1T (T = type strain), Entomoplasma melaleucae M-1T, Mesoplasma seiffertii F7T, Mesoplasma entomophilum TACT, Mesoplasma florum L1T, Mycoplasma fermentans PG18T, and Acholeplasma multilocale PN525T were similar in most respects. NADH ox activity was localized in the cytoplasm of these organisms. These strains had ATP-dependent PFK, MDH, LDH, ATP- and PPi-dependent dGUOK, and UNG activities, but not dUTPase or G6Pde activities. In contrast, Acholeplasma equifetale C112T, Acholeplasma oculi 19LT, Acholeplasma hippikon C1T, Acholeplasma modicum PG49T, and Acholeplasma morum 72-043T had membrane-localized NADH ox activity, PPi-dependent PFK, G6Pde, and dUTPase activities, and significantly lower MDH and LDH activities and exhibited a faster rate with PPi than with ATP in the dGUOK reaction. All of the members of the Mollicutes tested had hypoxanthine-guanine phosphoribosyl transferase, phosphoenolpyruvate carboxylase, and (except for Mesoplasma entomophilum TAC(T)) UNG activities. All of the Acholeplasma strains except Acholeplasma multilocale PN525T had TK, TMPK, and UNG activities. Mesoplasma entomophilum TAC(T) was distinguished by having no detectable dUTPase, UNG, TK, and TMPK activities, indicating that there is a severe restriction in or an absence of a synthetic route to dTTP. Our data also suggest that A. multilocale PN525T is a member of an unrecognized metabolic subgroup of the genus Acholeplasma or is not an Acholeplasma strain.

Competitive immunosorbent assays using ligand-enzyme conjugates bifunctional liposomes: theory and experiment

Two models of immunoadsorbent assays are developed that describe the competitive adsorption of labeled antigen and unlabeled analyte to antibody binding sites immobilized on a solid surface. In the first model, a small labeled antigen and a small unlabeled analyte compete with only binding site limitations and no steric limitations. A multicomponent langmuir isotherm results that is sufficient to quantify competitive adsorption. This model can describe, with no adjustable parameters, the data of competitive assays for biotin using biotinylated horseradish peroxidase (B-HRP) over a wide range of anti-biotin antibody (ABA) surface densities. In the second model, the small unlabeled analyte competes with a large colloidal particle containing many antigens and enzyme labels attached to its surface. This model quantifies the steric interference that large particles can experience upon binding (large ligand effect) due to the lower probability of finding an available area of the right size to accommodate the larger adsorbent. This large ligand model also takes into account the increased probability of binding a large particle due to the larger number of antibody binding sites covered per collision. The resulting model is used to analyze the competitive assay data of biotin competing with liposomes to which many biotin and HRP molecules have been conjugated. This analysis is of interest because previous work has shown that these bifunctional liposomes can reduce the detection limit for antigens in bulk solution relative to assays performed with conventional small labeled antigens.

Occurrence of rheumatoid arthritis is not increased in the first degree relatives of a population based inception cohort of inflammatory polyarthritis

OBJECTIVE

To determine the risk of rheumatoid arthritis (RA) in first degree relatives of a true population based sample of probands with inflammatory polyarthritis.

METHODS

In a case-control study, a two stage screening procedure was used to ascertain the prevalence of RA in 518 first degree relatives of 207 Norfolk Arthritis Register cases registered in 1990 and 414 first degree relatives of 180 local controls. An initial joint symptom and medical history questionnaire was followed by a physical examination, and serological and radiological evaluation of those with symptoms.

RESULTS

The prevalence of RA in the first degree relatives of all the Norfolk Arthritis Register cases was 7.7/1000, compared with 4.8/1000 in the first degree relatives of the controls, with a risk ratio of 1.6 (95% confidence interval 0.3 to 8.7). This very modest increase was also seen when the analysis was restricted to the first degree relatives of Norfolk Arthritis Register cases who satisfied the American Rheumatism Association criteria for RA: prevalence rate 7.2/1000.

CONCLUSION

There was no evidence of an important increased familial risk of RA in this community based sample. These data are compatible with others from immunogenetic studies showing only weak HLA associations with community ascertained RA.

Haemodynamic changes measured by transthoracic bioimpedance during treatment with recombinant human erythropoietin

Hypertension complicates the treatment of anaemia of chronic renal failure with recombinant human erythropoietin (EPO) in some patients. We conducted a prospective study measuring changes in cardiac index (CI) and systemic vascular resistance index (SVRI) in 29 patients from before commencement of EPO to attainment of target haemoglobin concentration. We used the operator-independent technique of trans-thoracic bioimpedance. The group of patients who developed EPO-induced hypertension (EpHT) were separately analysed and compared with the group who had no change in blood pressure (NC). Our results showed there was a significant rise in SVRI after treatment in EpHT group patients but in the NC group there was a small fall. CI increased significantly in the NC group after treatment but no change was recorded in the EpHT group. These findings clearly demonstrate how the cardiovascular changes differ in patients who develop EPO-induced hypertension.