Toward defining the role of the synovium in mitigating normal articular cartilage wear and tear

Cartilage repair has been studied extensively in the context of injury and disease, but the joint's management of regular sub-injurious damage to cartilage, or 'wear and tear,' which occurs due to normal activity, is poorly understood. We hypothesize that this cartilage maintenance is mediated in part by cells derived from the synovium that migrate to the worn articular surface. Here, we demonstrate in vitro that the early steps required for such a process can occur. First, we show that under physiologic mechanical loads, chondrocyte death occurs in the cartilage superficial zone along with changes to the cartilage surface topography. Second, we show that synoviocytes are released from the synovial lining under physiologic loads and attach to worn cartilage. Third, we show that synoviocytes parachuted onto a simulated or native cartilage surface will modify their behavior. Specifically, we show that synoviocyte interactions with chondrocytes lead to changes in synoviocyte mechanosensitivity, and we demonstrate that cartilage-attached synoviocytes can express COL2A1, a hallmark of the chondrogenic phenotype. Our findings suggest that synoviocyte-mediated repair of cartilage 'wear and tear' as a component of joint homeostasis is feasible and is deserving of future study.

Pneumopericardium after peritoneopericardial diaphragmatic hernia repair in a dog

A one-year-old neutered Goldendoodle presented for evaluation. One week prior to presentation, surgical closure of a peritoneopericardial diaphragmatic hernia (PPDH) was performed via ventral midline celiotomy. Since the procedure, the dog had been lethargic and anorexic at home. Thoracic radiographs revealed a pneumopericardium. Pericardiocentesis was performed which evacuated approximately 100 mL of air from the pericardial sac. The dog recovered well and began eating in the hospital and resumed normal activity. This is the first reported case of a pneumopericardium post-PPDH repair requiring pericardiocentesis. Clinicians should be aware of this rare complication in postoperative PPDH patients.

Toward Development of a Diabetic Synovium Culture Model

Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degradation and inflammation of synovium, the specialized connective tissue that envelops the diarthrodial joint. Type 2 diabetes mellitus (DM) is often found in OA patients, with nearly double the incidence of arthritis reported in patients with diabetes (52%) than those without it (27%). The correlation between OA and DM has been attributed to similar risk factors, namely increasing age and joint loading due to obesity. However, a potential causative link is not well understood due to comorbidities involved with treating diabetic patients, such as high infection rates and poor healing response caused by hyperglycemia and insulin resistance. The purpose of this study was to investigate the effect of hyperglycemic and insulin culture conditions on synovium properties. It was hypothesized that modeling hyperglycemia-induced insulin resistance in synovium would provide novel insights of OA pathogenesis in DM patients. To simulate DM in the synovial joint, healthy synovium was preconditioned in either euglycemic (EG) or hyperglycemic (HG) glucose concentrations with insulin in order to induce the biological response of the diseased phenotype. Synovium biochemical composition was evaluated to determine ECM remodeling under hyperglycemic culture conditions. Concurrent changes in AKT phosphorylation, a signaling pathway implicated in insulin resistance, were measured along with gene expression data for insulin receptors, glucose transporters, and specific glycolysis markers involved in glucose regulation. Since fluid shear stress arising during joint articulation is a relevant upstream stimulus for fibroblast-like synoviocytes (FLS), the predominant cell type in synovium, FLS mechanotransduction was evaluated via intracellular calcium ([Ca²⁺]_i). Incidence and length of primary cilia, a critical effector of cell mechanosensing, were measured as potential mechanisms to support differences in [Ca²⁺]_i responses. Hyperglycemic culture conditions decreased collagen and GAG content compared to EG groups, while insulin recovered ECM constituents. FLS mechanosensitivity was significantly greater in EG and insulin conditions compared to HG and non-insulin treated groups. Hyperglycemic treatment led to decreased incidence and length of primary cilia and decreased AKT phosphorylation, providing possible links to the mechanosensing response and suggesting a potential correlation between glycemic culture conditions, diabetic insulin resistance, and OA development.

Evaluation of owner medication adherence for canine cardiovascular disease in the referral setting

OBJECTIVE

To evaluate owners' medication adherence for management of cardiovascular disease in the small animal specialty setting.

ANIMALS, MATERIALS, AND METHODS

A questionnaire-based study of owners at a single, multispecialty, small animal referral center was conducted. Owners completed a written survey evaluating demographics, degree of medication adherence, and difficulties encountered for medication adherence. Owners were free to decline participation in the study.

RESULTS

Ninety-six questionnaires were completed during the study period. Fifty-four respondents (56.3%) reported treating their pet for over one year for cardiovascular disease, and myxomatous mitral valve disease was the most common diagnosis (76.0%). Twenty-nine (30.2%) respondents felt they could consistently administer a maximum of three medications daily, and 46 (47.9%) respondents reported twice-daily dosing was the highest frequency of administration that could be consistently achieved. Twenty-two respondents (22.9%) reported that their pet required daily medications for at least one other chronic condition besides cardiac disease. Seventeen respondents (17.7%) reported at least occasionally missing medications, although only one (1.0%) reported it was more than 20% of medications per week.

CONCLUSIONS

Medication adherence was high in this study population. Almost one-half of owners surveyed reported being unable to consistently administer more than three medications daily, and approximately one-quarter of patients were treated for at least one additional chronic condition requiring daily medications, in addition to cardiac disease. Clinicians should be aware of these factors when determining optimal treatment protocols for the management of cardiovascular disease in dogs.

Attachment of cartilage wear particles to the synovium negatively impacts friction properties

Cartilage wear particles are released into the synovial fluid by mechanical and chemical degradation of the articular surfaces during osteoarthritis and attach to the synovial membrane. Accumulation of wear particles could alter key tissue-level mechanical properties of the synovium, hindering its characteristically low-friction interactions with underlying articular surfaces in the synovial joint. The present study employs a custom loading device to further the characterization of native synovium friction properties, while investigating the hypothesis that attachment of cartilage wear particles increases friction coefficient. Juvenile bovine synovium demonstrated characteristically low friction coefficients in sliding contact with glass, in agreement with historical measurements. Friction coefficient increased with higher normal load in saline, while lubrication with native synovial fluid maintained low friction coefficients at higher loads. Cartilage wear particles generated from juvenile bovine cartilage attached directly to synovium explants in static culture, with incorporation onto the tissue denoted by cell migration onto the particle surface. In dilute synovial fluid mimicking the decreased lubricating properties during osteoarthritis, wear particle attachment significantly increased friction coefficient against glass, and native cartilage and synovium. In addition to providing a novel characterization of synovial joint tribology this work highlights a potential mechanism for cartilage wear particles to perpetuate the degradative environment of osteoarthritis by modulating tissue-level properties of the synovium that could impact macroscopic wear as well as mechanical stimuli transmitted to resident cells.

Evaluation of owners' attitudes towards veterinary insurance in a specialty hospital

OBJECTIVES

The purpose of this study was to investigate the frequency and perception of veterinary insurance among owners' at a small animal specialty hospital around a large urban city.

MATERIALS AND METHODS

A questionnaire evaluated the prevalence and perception of insurance among owners at a small animal specialty hospital over a 2 month period. Respondents provided demographic information including age, sex, educational level and household income. Respondents without insurance were asked reasons for not having insurance, approximate cost of insurance per month desired and percentage of coverage of medical expenses they would want insurance to provide. Respondents with insurance were asked how they chose their current plan, how it affects their medical decisions for their pet and their overall satisfaction.

RESULTS

Sixty-seven (28.5%) owners reporting having insurance for at least one pet. Owners most commonly selected their current insurance plan based on online research (27, 40.3%). Fifty-two respondents (77.6%) reported being satisfied with their insurance plan and 49 (73.2%) stated that would recommend their current insurance plan to a friend.

CLINICAL SIGNIFICANCE

Insurance had a relatively high prevalence in this study group with most owners being satisfied with their current plan and would be likely to recommend it to a friend. The role of insurance in how it affects owner's medical decisions, care for their pet and interactions with veterinarians in companion animal medicine requires further evaluation.

Cartilage Wear Particles Induce an Inflammatory Response Similar to Cytokines in Human Fibroblast-Like Synoviocytes

The synovium plays a key role in the development of osteoarthritis, as evidenced by pathological changes to the tissue observed in both early and late stages of the disease. One such change is the attachment of cartilage wear particles to the synovial intima. While this phenomenon has been well observed clinically, little is known of the biological effects that such particles have on resident cells in the synovium. The present work investigates the hypothesis that cartilage wear particles elicit a pro-inflammatory response in diseased and healthy human fibroblast-like synoviocytes, like that induced by key cytokines in osteoarthritis. Fibroblast-like synoviocytes from 15 osteoarthritic human donors and a subset of three non-osteoarthritic donors were exposed to cartilage wear particles, interleukin-1α or tumor necrosis factor-α for 6 days and analyzed for proliferation, matrix production, and release of pro-inflammatory mediators and degradative enzymes. Wear particles significantly increased proliferation and release of nitric oxide, interleukin-6 and -8, and matrix metalloproteinase-9, -10, and -13 in osteoarthritic synoviocytes, mirroring the effects of both cytokines, with similar trends in non-osteoarthritic cells. These results suggest that cartilage wear particles are a relevant physical factor in the osteoarthritic environment, perpetuating the pro-inflammatory and pro-degradative cascade by modulating synoviocyte behavior at early and late stages of the disease. Future work points to therapeutic strategies for slowing disease progression that target cell-particle interactions. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1979-1987, 2019.

The effect of atorvastatin on haemostatic parameters in apparently healthy dogs

OBJECTIVE

To determine the effect of atorvastatin on haemostatic parameters as measured by prothrombin time, activated partial thromboplastin time and thromboelastography in apparently healthy dogs administered 2 mg/kg orally once daily for 1 week.

MATERIALS AND METHODS

Prospective study of 20 apparently healthy client-owned dogs at a small animal specialty hospital. Dogs had a baseline complete blood count, serum chemistry profile, fibrinogen, platelet count, prothrombin time, activated partial thromboplastin time and thromboelastography performed. Each dog was then administered approximately 2 mg/kg of atorvastatin orally once daily for 1 week, and the laboratory tests were repeated. Adverse effects attributed to atorvastatin were recorded.

RESULTS

All 20 enrolled dogs completed the study. Dogs received a median dose of 2.06 mg/kg (range 1.94 to 2.44 mg/kg) atorvastatin once daily, which was associated with a significant increase in pulse rate, mean corpuscular haemoglobin concentration, albumin and a significant decrease in mean corpuscular volume, cholesterol and lipase values compared with baseline. On thromboelastography, there was a significant increase in maximum amplitude, G, coagulation index, amplitude at 30 minutes, amplitude at 60 minutes and significant decrease in percentage of clot lysed at 30 minutes and percentage of clot lysed at 60 minutes values compared with baseline. Six dogs had a noticeable increase in appetite.

CLINICAL SIGNIFICANCE

The results of this study suggest that atorvastatin may produce a procoagulant effect in dogs, although the clinical significance is unclear. Polyphagia was the most commonly reported adverse effect.

Effect of client complaints on small animal veterinary internists

OBJECTIVES

To investigate the effect of client complaints on small animal veterinary internists' welfare, job satisfaction and medical practices.

MATERIALS AND METHODS

Cross-sectional anonymous survey study. Between February 1 and March 31, 2017, a web-based questionnaire was made available through the American College Veterinary Internal Medicine sub-specialty Small Animal Internal Medicine E-mail List Serve.

RESULTS

A total of 92 completed surveys were available for review. Fifty-nine (64∙1%) respondents received a client complaint during the previous 6 months with cost of care the most common reason (53∙3%). Eighty-nine (96∙7%) respondents worry about client complaints being made against them with 33 (35∙8%) stating they worry "most of the time" or "all of the time." Thirty-two (34∙8%) reported being verbally assaulted by a client in the previous 6 months and 27 (29∙4%) reported being threatened with litigation during the previous 6 months. Sixty-six (71∙7%) have reported changing the way they practice medicine to avoid a client complaint and 40 (43∙5%) have considered changing their career because of complaints made against them.

CLINICAL RELEVANCE

Client complaints are a frequent problem among small animal veterinary internists that have detrimental effects on job satisfaction, psychological distress and medical practices.

Fibroblast-like synoviocyte mechanosensitivity to fluid shear is modulated by interleukin-1α

Fibroblast-like synoviocytes (FLS) reside in the synovial membrane of diarthrodial joints and are exposed to a dynamic fluid environment that presents both physical and chemical stimuli. The ability of FLS to sense and respond to these stimuli plays a key role in their normal function, and is implicated in the alterations to function that occur in osteoarthritis (OA). The present work characterizes the response of FLS to fluid flow-induced shear stress via real-time calcium imaging, and tests the hypothesis that this response is modulated by interleukin-1α (IL-1α), a cytokine elevated in OA. FLS demonstrated a robust calcium signaling response to fluid shear that was dose dependent upon stress level and required both external and internal calcium sources. Preconditioning with 10ng/mL IL-1α for 24h heightened this shear stress response by significantly increasing the percent of responding cells and peak magnitude, while significantly decreasing the time for a peak to occur. Intercellular communication via gap junctions was found to account for a portion of the FLS population response in normal conditions, and was significantly increased by IL-1α preconditioning. IL-1α was also found to significantly increase average length and incidence of the primary cilium, an organelle commonly implicated in shear mechanosensing. These findings suggest that the elevated levels of IL-1α found in the OA environment heighten FLS sensitivity to fluid shear by altering both intercellular communication and individual cell sensitivity, which could affect downstream functions and contribute to progression of the disease state.

Surgical correction of gastro-oesophageal intussusception with bilateral incisional gastropexy in three dogs

Three dogs presented for evaluation of acute onset tachypnoea and dyspnoea following episodes of vomiting and/or regurgitation. Thoracic radiographs were suggestive of a gastro-oesophageal intussusception in all three dogs; one dog also showed evidence of aspiration pneumonia. All three dogs underwent surgical correction with a bilateral incisional gastropexy. All dogs recovered from anaesthesia uneventfully and were discharged from the hospital 3 days after presentation. Persistent megaoesophagus was evident in all three dogs, and they are being chronically managed with a strict feeding regime and pro-motility agents.

Influence of fatigue on construction workers' physical and cognitive function

BACKGROUND

Despite scientific evidence linking workers' fatigue to occupational safety (due to impaired physical or cognitive function), little is known about this relationship in construction workers.

AIMS

To assess the association between construction workers' reported fatigue and their perceived difficulties with physical and cognitive functions.

METHODS

Using data from a convenience sample of US construction workers participating in the 2010-11 National Health Interview Survey two multivariate weighted logistic regression models were built to predict difficulty with physical and with cognitive functions associated with workers' reported fatigue, while controlling for age, smoking status, alcohol consumption status, sleep hygiene, psychological distress and arthritis status.

RESULTS

Of 606 construction workers surveyed, 49% reported being 'tired some days' in the past 3 months and 10% reported 'tired most days or every day'. Compared with those feeling 'never tired', workers who felt 'tired some days' were significantly more likely to report difficulty with physical function (adjusted odds ratio [AOR] = 2.03; 95% confidence interval [CI] 1.17-3.51) and cognitive function (AOR = 2.27; 95% CI 1.06-4.88) after controlling for potential confounders.

CONCLUSIONS

Our results suggest an association between reported fatigue and experiencing difficulties with physical and cognitive functions in construction workers.

Is hypoallergenic a credible term?

Hypoallergenic is a term that is frequently applied to cosmetics and is intended to imply a very low likelihood of developing or potentiating allergic cutaneous reactions. However there are neither industry standards nor legal requirements which must be fulfilled in order to make this claim. We describe a 25-year-old woman referred with worsening eczema which she related to the use of two skincare products. Both had been promoted as hypoallergenic and 'preservative free'; chemical analysis using HPLC confirmed the presence of methyldibromoglutaronitrile and formaldehyde, both at robust concentrations. We consider it unlikely that these were present as contaminants and suggest that the term hypoallergenic must be interpreted with caution.

Structural analysis of an offset-keel design glenoid component compared with a center-keel design

Many different designs of glenoid prostheses have been developed in an attempt to reduce the loosening rates and improve the prognosis of total shoulder arthroplasty. This study investigated a design in which the keel is positioned anterior to the central plane of the component, an offset-keel design. The primary purpose of anterior location of the keel is to avoid contact between the keel and the cortical bone surface. However, anterior placement of the keel also situates it more directly under the line of action of the contact force in abduction; this has the possible advantage of reducing the bending stress on the cement mantle. Our purpose was to establish whether an offset-keel design reduces the cement stresses below those obtained with conventional central-keel designs. A computed tomography-based finite element model of the glenoid region is used and dynamic loading for 0 degrees to 180 degrees in both flexion and abduction is simulated with the use of data from van der Helm (J Biomech 1994;27:527-50). Finite element analyses are carried out for both the normal and the rheumatoid arthritic case. For the rheumatoid arthritic joint, a Larsen grade IV type destruction is reproduced and proximal subluxed loads are applied, associated with a deficient rotator cuff for 0 degrees to 180 degrees in flexion and abduction. Results predict that the cement mantle in the offset-keel design is much less stressed compared with that in the center-keel design for the maximum glenohumeral joint load in abduction for both the normal and the rheumatoid arthritis case. In flexion the offset-keel design still has lower cement stresses even though the load is acting on the opposite side of the glenoid cup from the keel; one explanation for this is that insertion of the offset keel involves removal of the lower stiffness cancellous bone, leaving the glenoid component flanges to be supported by the stronger bone remaining in the glenoid cavity. From a biomechanical point of view, the advantages of an offset-keel design would appear to be considerable.

Scabies management in the community

BACKGROUND

Unidentified and undertreated cases of scabies are the source of continued spread.

AIMS

To evaluate management of scabies in the community.

METHODS

Eighty-six outpatient and ward referrals were reviewed. Fifty-six had previously applied scabicidal treatments (Group 1), whilst in 30 patients the diagnosis was made de novo (Group 2). Treatment failure was identified by a detailed questionnaire. In both groups, patients were reviewed at four to six weeks.

RESULTS

Sixty-four per cent of Group 1 was initially correctly diagnosed. Seventy per cent of Group 1 patients had received verbal and written instruction as part of previous unsuccessful treatments. The clearance rate in the combined group treated according to protocol was 96%; 100% clearance was ultimately achieved.

CONCLUSION

Inconsistency in diagnosis and treatment of patients is common. A treatment protocol should be made available to family practitioners.

Three-dimensional finite element analysis of glenoid replacement prostheses: a comparison of keeled and pegged anchorage systems

Glenoid component loosening is the dominant cause of failure in total shoulder arthroplasty. It is presumed that loosening in the glenoid is caused by high stresses in the cement layer. Several anchorage systems have been designed with the aim of reducing the loosening rate, the two major categories being "keeled" fixation and "pegged" fixation. However, no three-dimensional finite element analysis has been performed to quantify the stresses in the cement or to compare the different glenoid prosthesis anchorage systems. The objective of this study was to determine the stresses in the cement layer and surrounding bone for glenoid replacement components. A three-dimensional model of the scapula was generated using CT data for geometry and material property definition. Keeled and pegged designs were inserted into the glenoid, surrounded by a 1-mm layer of bone cement. A 90 deg arm abduction load with a full muscle and joint load was applied, following van der Helm (1994). Deformations of the prosthesis, stresses in the cement, and stresses in the bone were calculated. Stresses were also calculated for a simulated case of rheumatoid arthritis (RA) in which bone properties were modified to reflect that condition. A maximum principal stress-based failure model was used to predict what quantity of the cement is at risk of failure at the levels of stress computed. The prediction is that 94 percent (pegged prosthesis) and 68 percent (keeled prosthesis) of the cement has a greater than 95 percent probability of survival in normal bone. In RA bone, however, the situation is reversed where 86 percent (pegged prosthesis) and 99 percent (keeled prosthesis) of the cement has a greater than 95 percent probability of survival. Bone stresses are shown to be not much affected by the prosthesis design, except at the tip of the central peg or keel. It is concluded that a "pegged" anchorage system is superior for normal bone, whereas a "keeled" anchorage system is superior for RA bone.

Gianotti-Crosti syndrome in an infant following immunization

Gianotti-Crosti syndrome (GCS) is a distinctive, self-limiting acropapular or papulovesicular eruption. Typical clinical presentation is that of a monomorphic, nonpruritic eruption most commonly involving the face, neck, buttocks, and extremities. It tends to occur in childhood, though infrequently it has been reported in adults. We report GCS occurring in an infant following immunization.

Hyperthermia induces resistance to ultraviolet light B in primary and immortalized epidermal keratinocytes

Environmental exposure to UVB (290-320 nm) wavelengths of the solar spectrum causes major damage, including carcinogenesis, in the skin. Therefore, cellular responses that protect against UVB damage are of particular interest in cutaneous epithelial cells. In cultured keratinocytes, mild hyperthermia generates a classical stress response with acquired thermotolerance and elevated stress protein synthesis (E. V. Maytin, J. Biol. Chem., 267: 23189-23196, 1992). To test the ability of this stress response to protect against UVB damage, monolayers of primary murine keratinocytes or BALB/MK keratinocytes were heated at 42 degrees C for 1 h and then exposed to UVB at 6 h (typical dose, 40 mJ/cm2). Survival was assessed by fluorescein diacetate/ethidium bromide vital dye uptake and video microscopy. With heat-conditioning prior to UVB, a significant increase in both the percentage viability (2- to 3-fold) and in the absolute number of living (fluorescein diacetate-positive) cells was measurable at 24-48 h. Steady-state incorporation into [3H]DNA and 35S-protein, while suppressed immediately after UVB, showed greater recovery in heat-conditioned cultures compared to sham-conditioned cultures at 48 h. Increased metabolic activity was accompanied by increased proliferative potential since colonies of BALB/MK cells observed at 72 h were larger, more numerous, and more active in the uptake of 5-bromo-2'-deoxyuridine in heat-conditioned cultures. A time course for the development of UVB resistance showed maximal protection when heat and UVB were spaced approximately 6 h apart. Hyperthermic conditioning could induce UVB protection in nonproliferating cells, indicating that cell cycle arrest was not primarily responsible for the UVB-protective effect. In summary, hyperthermia induces a mechanism in epithelial cells which can ameliorate damage from UVB.

In vitro evidence that bone formation may be coupled to resorption by release of mitogen(s) from resorbing bone

Bone-derived proteins have been shown to stimulate the proliferation of bone-forming cells and to increase the rate of embryonic bone formation in vitro. The current studies were intended to determine the tissue distribution of bone cell-active mitogen(s) in the embryonic chick, to determine the cellular origin and the target cell specificity of the bone cell-active mitogen(s) in embryonic chick bone, to determine whether the release of mitogenic activity from embryonic chick tibiae was proportional to bone resorption, and to compare mitogenic activities prepared from different skeletal sources, with respect to Mr, chemical stability, and mitogen activity kinetics. A bone cell-active mitogen(s) was identified in extracts of bone and cartilage but not in extracts of muscle, liver, intestine, or brain. (Mitogenic activity was determined as increased incorporation of 3[H]-thymidine into DNA in serum-free, calvarial cell cultures.) Together, the following three observations indicate an osteoblastic origin for the bone cell-active mitogen(s) in chick bone. First, the mitogen content of embryonic chick tibiae increased 4.5-fold, during eight days of serum-free in vitro growth (P less than .005). Second, conditioned medium (CM) from serum-free monolayer cultures of calvarial cells contained bone cell-active mitogen(s), but CM from parallel cultures of skin, liver, and intestinal cells did not. And, finally, the amount of bone cell-active mitogen(s) in calvarial cell CM was correlated with the amount of alkaline phosphatase (ALP) activity per cell, ie, an index of osteoblastic differentiation (r = .92, P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate binding studies on the Bandeiraea simplicifolia I isolectins. Lectins which are mono-, di-, tri-, and tetravalent for N-acetyl-D-galactosamine

Association constants for the binding of methyl alpha-D-galactopyranoside (methyl alpha-D-Galp) and methyl 2-acetamido-2-deoxy-alpha-D-galactopyranoside (methyl alpha-D-GalNAcp) to three Bandeiraea simplicifolia isolectins (A4, A2B2, B4) were determined by equilibrium dialysis and fluorescence enhancement measurements. The a and B subunits appear to have approximately the same Kassoc for methyl alpha-D-Galp: 1.45 X 10(4), 1.98 X 10(4), and 2.06 X 10(4) M-1 for A4, A2B2, and B4, respectively, as determined by equilibrium dialysis. Fluorescence enhancement measurements on B4 gave an association constant of 2.07 X 10(4) M-1 for methyl alpha-D-Galp and 1.87 X 10(3) M-1 for methyl beta-D-galp. By equilibrium dialysis, we were able to detect 3.3 (theory, 4.0) methyl alpha-D-GalNAcp binding sites for A4 (Kassoc = 1.87 X 10(5) M-1), 1.9 for A2B2 (Kassoc = 1.19 X 10(5) M-1), and were unable to detect any methyl alpha-D-GalNAcp binding sites for B4. However, four very weak methyl alpha-D-GalNAc binding sites for B4 were detected by fluorescence enhancement measurement (Kassoc = 1.26 X 10(2) M-1). Thus, the A subunit has an affinity for methyl alpha-D-GalNAc 3 orders of magnitude greater than the B subunit. Precipitation and hapten inhibition data are in accord with these binding measurements. Toward guaran and type B blood group substance, all isolectins precipitated the same amount of biopolymer. However, AB3, A2B2, and A3B, which are mono-, di-, and trivalent for alpha-D-GalNAcp, were differentially precipitated by type A blood group substance which contains alpha-D-GalNAcp-end groups. A3B precipitated the most, A2B2 less, and AB3 no type A substance. These isolectins should prove useful in studies evaluating the effect of valence on lectin-cell interaction.

Physical-chemical characterization and carbohydrate-binding activity of the A and B subunits of the Bandeiraea simplificolia I isolectins

Bandeiraea simplicifolia I plant seed isolectins comprise a family of tetrameric alpha-D-galactopyranosyl-binding glycoproteins composed of various combinations of teo different kinds of subunits designated A and B. Subtypes of the A (Aa, Ab, Ac, Ad, and Ae) and B (Ba, Bb, Bc, Bd, and Be) subunits were demotypes varies from seed to seed (e.g., some seeds contain only B subunits, others only A subunits), subtypes Ac and Bc predominate in a natural mixture of the isolectins. Two-dimensional agar gel diffusion studies indicate that, in addition to common structural features, each subunit contains its own distinct antigenic determinants. Although the A and B subunits have closely similar amino acid compositions, they differ markedly in one respect: the B subunit has one methionine residue whereas the A subunit contains no methionine. The neutral carbohydrate content of both subunits is identical. The ability of biopolymers and synthetic glycoproteins to precipitate A4 and B4, as well as the capacity of sugars and oligosaccharides to inhibit precipitate formation, was examined. On the basis of these studies, it is suggested that hydrogen bonding occurs between the hydrogen atoms of the C-3 and C-4 hydroxyl groups of alpha-D-GalNAcp and alpha-D-galp units and the A and B subunits, respectively.

Abnormal lymphocyte responses in residents of a town with a cluster of Hodgkin's disease

A time-space aggregate of Hodgkin's disease was observed in a small town. A large elevator for the storage of navy beans was located in the residential area of the town. Lymphocytes of town residents compared to those of non-residents showed increased levels of transformations when challenged with extracts of navy beans. A phytohaemagglutinin from navy beans with the ability to stimulate lymphocytes was isolated and characterized. A hypothesis concerning a connection between this cluster of Hodgkin's disease and the abnormal lymphocyte responses to navy-bean phytohaemagglutinin is discussed.

An anti-B reagent prepared from the alpha-D-galactopyranosyl-binding isolectins from Bandeiraea simplicifolia seeds

A method for the large scale preparation of the alpha-D-galactosyl binding isolectins from Bandeiraea simplicifolia seeds using an absorbent prepared by linking D-galactosamine to CH-Sepharose is described. The addition of N-acetyl-D-galactosamine (GalNAc) to these isolectins produced an anti-B reagent (BS I + GalNAc anti-B). Although BS I + GalNAc anti-B readily agglutinated red blood cells from the majority of group B and AB donor and patient blood samples tested, it reacted weakly with group B and AB cord red blood cells and failed to agglutinate five of 100 group AB donor blood samples when tested by an automated technique. The reagent did not agglutinate the red blood cells from seven acquired-B red blood cell samples and was strongly reactive with Tn-polyagglutinable red blood cells. These findings indicate that this lectin anti-B preparation may be of more value in investigative immunohematology, rather than as an alternative to human group A serum as a source of anti-B for blood-typing purposes. The results of tests on Tn-polyagglutinable red blood cells with BS I + GalNAc anti-B and the purified isolectins BS I(A4) and BS I(B4) are also presented, and discussed in relation to current concepts on the structure of the Tn receptor.

Five alpha-D-galactopyranosyl-binding isolectins from Bandeiraea simplicifolia seeds

The alpha-D-galactopyranosyl-binding lectin previously purified from Bandeiraea simplicifolia seeds (Hayes, C.H., and Goldstein, I.J. (1974) J. Biol. Chem. 249, 1904) is shown to consist of five isolectins separable on polyacrylamide gel electrophoresis at pH 9.5. The isolectins are tetrameric structures composed of various combinations of two different glycoprotein subunits designated A and B. The A and B subunits appear to be immunochemically indistinguishable against rabbit antisera prepared from the isolectin mixture. The A subunit contains no methionine, whereas the B subunit contains 1 residue. The subunits migrate differently on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and, although each subunit contains 1 residue of cysteine, they react differently toward 5,5'-dithiobis(2-nitrobenzoic acid). The carbohydrate binding specificity of the two subunits differs significantly: the A subunit exhibits a primary specificity for alpha-D-GalNAcp but also reacts with alpha-D-Galp units, whereas the B subunit shows a sharp specificity toward alpha-D-Galp residues. The differences in carbohydrate binding specificity were exploited in separating the isolectins. B. simplicifolia I isolectins (A4) and (A3B) were purified on a Bio-Gel melibionate column, and (A2B2), (AB3), and (B4) were separated on a column of insolubilized blood group A substance.