Functional Outcomes of Congenital Scoliosis at a Mean 35-Year Follow-up Post In Situ Fusion. Revisiting Patients From the 2002 Goldberg et al Study

BACKGROUND

The management of congenital scoliosis poses a significant challenge for treating surgeons. The aim of our study was to provide insight into the long-term clinical results of spinal fusion in congenital scoliosis.

METHODS

We performed a retrospective review of the scoliosis database in our institution for the period 1976 until 2002 identifying 43 patients with congenital scoliosis who underwent spinal fusion. Patient demographics, diagnosis, levels fused, and radiographs were evaluated. Patients were evaluated for unplanned return to the operating room (UPROR) via SRS 22, EQ5D-5L, and Oswestry Disability Index (ODI).

RESULTS

Of the 43 patients who fulfilled the inclusion criteria, 22 patients agreed to participate, 3 patients were known to be deceased and 18 patients were lost to follow-up or declined to participate and were excluded. The mean age of the respondents was 40.7 years (range, 30 to 47 y) with a mean follow-up from index surgery of 35 years (range, 20 to 44 y). At most recent follow-up, 12 patients (54%) underwent UPROR. The mean age at diagnosis was 3.4 years (range, birth to 11.5 y), and the mean age for first surgery was 5.8 years (range, 1 to 13 y). As regards radiologic follow-up; the mean number of levels fused was 5.2 (range, 2 to 12). Thoracic fusion was performed in 17 patients (77%). The mean T1 to T12 height at index surgery and maturity was 166 mm (range, 130 to 240 mm) and 202 mm (range, 125 to 270 mm), respectively. The mean functional scores at follow-up were SRS 22: 4.5 (range, 2.4 to 5), cumulative EQ5D-5L score 7.2 (range, 5 to 15), and ODI: 8% (range, 2 to 30%). All respondents completed high school, 10 patients (45%) completed university, and 2 patients were awarded doctorates. Currently, 17 patients (77%) are in paid employment.

CONCLUSIONS

This report constitutes the largest series of patients treated by spinal arthrodesis for congenital scoliosis followed into maturity. We demonstrate the thorax continues to grow after index fusion, patient-reported outcomes were satisfactory with superior educational and employment rates and unplanned return to theatre is rare in adult life.

LEVEL OF EVIDENCE

Therapeutic Level IV.

36 WHAT DO OLDER ADULTS AND HEALTH CARE PROFESSIONALS LOOK FOR IN A FOOD PRODUCT?

Background

The Mediterranean diet (Medi-diet) has proven benefits for healthy ageing but isn’t the habitual diet of most middle-aged or older adults in Ireland; there can be accessibility and tolerability issues with high amounts of fresh fruit and vegetables. Providing key Medi-diet nutrients in a food product is a novel approach to this challenge. This research aims to explore what ‘younger-old’ adults and healthcare professionals (HCPs) would value in such a novel food product.

Methods

Semi-structured 1:1 interviews and Focus Groups (FGs) were conducted remotely from July 2021 to January 2022. Older adults, defined as over 55’s, were recruited through relevant social, retirement and disease-support groups. Purposive sampling recruited a gender balance and a range of ages and disease profiles. HCPs were recruited through researcher networks and professional associations. Interviews/FGs were recorded, transcribed, and subsequently examined using inductive thematic analysis.

Results

Older adults (n=47; 50% male) were mostly aged 60-69 years (48.9%). Recruited HCPs (n=26) included dieticians (n=8); geriatricians (n=5); therapists (n=4); and nurses, pharmacists, catering managers (community; residential), and meal delivery service coordinators (n=2 each). Participants supported a food product for older adults requiring a nutrient-dense “boost”, or supplementary fibre or protein, but generally preferred a “food-first” approach, as opposed to a “silver bullet” product. Older adults largely associated functional foods with probiotic products “to repair the gut”, something to have “every now and then”. Product texture and portion size should consider changing dentition and appetite, and consider packaging (dexterity) and preparation ease, but should not stigmatize older adults through targeted branding. Participants felt pre-made soups or cake-type bars would be appealing, but not drinks.

Conclusion

A novel food product could supplement a balanced diet for older adults, providing high-protein content, and high-fibre for gut health, complimenting an overall lifestyle approach to health improvement and disease prevention.

Paediatric major trauma in the setting of the Irish trauma network

BACKGROUND

The construction of a new tertiary children's hospital and reconfiguration of its two satellite centres will become the Irish epicentre for all paediatric care including paediatric trauma. Ireland is also currently establishing a national trauma network although further planning of how to manage paediatric trauma in the context of this system is required. This research defines the unknown epidemiology of paediatric major trauma in Ireland to assist strategic planning of a future paediatric major trauma network.

METHODS

Data from 1068 paediatric trauma cases was extracted from a longitudinal series of annual cross-sectional studies collected by the Trauma Audit and Research Network (TARN). All paediatric patients between the ages of 0-16 suffering AIS ≥2 injuries in Ireland between 2014-2018 were included. Demographics, injury patterns, hospital care processes and outcomes were analysed.

RESULTS

Children were most commonly injured at home (45.1%) or in public places/roads (40.1%). The most frequent mechanisms of trauma were falls <2 m (36.8%) followed by RTAs (24.3%). Limb injuries followed by head injuries were the most often injured body parts. The proportion of head injuries in those aged <1 year is double that of any other age group. Only 21% of patients present directly to a children's hospital and 46% require transfer. Consultant-led emergency care is currently delivered to 41.5% of paediatric major trauma patients, there were 555 (48.2%) patients who required operative intervention and 22.8% who required critical care admission. A significant number of children in Ireland aged 1-5 years die from asphyxia/drowning. The overall mortality rate was 3.8% and was significantly associated with the presence of head injuries (p < 0.001).

CONCLUSION

Paediatric Trauma represents a significant childhood burden of mortality and morbidity in Ireland. There are currently several sub-optimal elements of paediatric trauma service delivery that will benefit from the establishment of a trauma network. This research will help guide prevention strategy, policy-making and workforce planning during the establishment of an Irish paediatric trauma network and will act as a benchmark for future comparison studies after the network is implemented.

Triplane Fracture of the Distal Femur in the Paediatric Population: A Case Report and Literature Review

Triplane fractures of the distal femur in paediatric populations are extremely rare. Only three cases of paediatric triplane fractures of the distal femur are described in the literature. Our aim is to add to the scant literature on triplane fractures of the distal femur in the paediatric population. The majority of trauma and orthopaedic surgeons are not expected to come across this injury throughout their careers. A CT is recommended to plan surgery, and subsequent follow up is crucial to provide the child with the best possible outcome. In particular, follow up is important to monitor for any abnormal growth or deformities. 

Transanal endoscopic microsurgery for rectal lesions in a specialist regional early rectal cancer centre: the Mersey experience

AIM

Organ-preserving local excision by transanal endoscopic microsurgery (TEM) for early rectal cancer offers significantly lower morbidity as compared to formal rectal cancer resection with acceptable outcomes. This study presents our 6-year experience of TEM for rectal lesions referred to a specialist early rectal cancer centre in the UK.

METHOD

Data were collected for all patients referred for TEM of suspected early rectal cancer to a regional specialist early rectal cancer multidisciplinary team (MDT) over a 6-year period.

RESULTS

One hundred and forty-one patients who underwent full-thickness TEM for suspected or confirmed early rectal cancer were included. Thirty patients were referred for TEM following incomplete endoscopic polypectomy. Final pathology was benign in 77 (54.6%) cases and malignant in 64 (45.4%). Of the 61 confirmed adenocarcinomas, TEM resections were pT0 in 17 (27.9%), pT1 in 32 (51.7%), pT2 in 11 (18.0%) and pT3 in 1 (1.6%). Thirty-eight of 61 patients (62.3%) had one or more poor histological prognostic features and these patients were offered further treatment. Twenty-three of 61 (37.7%) patients with rectal adenocarcinoma required no further treatment following TEM. Forty-three cases of rectal adenocarcinoma were available for establishing recurrence rates. Two of 43 patients (4.7%) developed a recurrence at a median follow-up of 28.7 months (12.1-66.5 months). The overall estimated 5-year overall survival rate was 87.9% and the disease-free survival rate was 82.9%.

CONCLUSION

Acceptable outcomes are possible for TEM surgery with appropriate patient selection, effective technique, expert histopathology, appropriate referral for adjuvant treatment and meticulous follow-up. This can be achieved through an early rectal cancer MDT in a dedicated specialist regional centre.

Self-assembly behaviour of hetero-nuclear Janus dumbbells

We investigate the fluid structure and self-assembly of a system of Janus dumbbells by means of aggregation-volume-bias Monte Carlo simulations and Simulated Annealing techniques. In our approach, Janus dumbbells model asymmetric colloidal particles constituted by two tangent (touching) spheres (labelled as h and s) of different sizes and interaction properties: specifically, the h spheres interact with all other spheres belonging to different dumbbells via hard-sphere potentials, whereas two s spheres interact via a square-well potential. By introducing a parameter α ∈ [0,2] that controls the size ratio between the h and s spheres, we are able to investigate the overall phase behaviour of Janus dumbbells as a function of α. In a previous paper (O'Toole et al., Soft Matter, 2017, 13, 803) we focused on the region where the s sphere is larger than the h sphere (α > 1), documenting the presence of a variety of phase behaviours. Here we investigate a different regime of size ratios, predominantly where the hard sphere is larger than (or comparable to) the attractive one. Under these conditions, we observe the onset of many different self-assembled super-structures. Depending on the specific value of α we document the presence of spherical clusters (micelles) progressively evolving into more exotic structures including platelets, filaments, networks and percolating fluids, sponge structures and lamellar phases. We find no evidence of a gas-liquid phase separation for α ≤ 1.1, since under these conditions it is pre-empted by the development of self-assembled phases.

Alice in Wonderland Syndrome: A real life version of Lewis Carroll's novel

Alice in Wonderland Syndrome was originally coined by Dr. John Todd in 1955. The syndrome is named after the sensations experienced by the character Alice in Lewis Carroll's novel Alice's Adventures in Wonderland. Alice in Wonderland Syndrome consists of metamorphopsia (seeing something in a distorted fashion), bizarre distortions of their body image, and bizarre perceptual distortions of form, size, movement or color. Additionally, patients with Alice in Wonderland Syndrome can experience auditory hallucinations and changes in their perception of time. Currently, there is no known specific cause of Alice in Wonderland Syndrome. However, theories point to infections such as the Epstein-Barr virus, medications such as topiramate and associated migraines. Neuroimaging studies have revealed brain regions involved with the manifestation of symptoms. These include the temporo-parietal junction within the temporal lobe and the visual pathway, specifically the occipital lobe. There are no current treatments for Alice in Wonderland Syndrome. Further research is needed to find better treatments for Alice in Wonderland Syndrome and to elucidate the exact cause or causes of Alice in Wonderland Syndrome.

Phase diagram of heteronuclear Janus dumbbells

Using aggregation-volume-bias Monte Carlo simulations along with successive umbrella sampling and histogram re-weighting, we study the phase diagram of a system of dumbbells formed by two touching spheres having variable sizes, as well as different interaction properties. The first sphere (h) interacts with all other spheres belonging to different dumbbells with a hard-sphere potential. The second sphere (s) interacts via a square-well interaction with other s spheres belonging to different dumbbells and with a hard-sphere potential with all remaining h spheres. We focus on the region where the s sphere is larger than the h sphere, as measured by a parameter 1 ≤ α ≤ 2 controlling the relative size of the two spheres. As α → 2 a simple fluid of square-well spheres is recovered, whereas α → 1 corresponds to the Janus dumbbell limit, where the h and s spheres have equal sizes. Many phase diagrams falling into three classes are observed, depending on the value of α. The 1.8 ≤ α ≤ 2 is dominated by a gas-liquid phase separation very similar to that of a pure square-well fluid with varied critical temperature and density. When 1.3 ≤ α ≤ 1.8 we find a progressive destabilization of the gas-liquid phase diagram by the onset of self-assembled structures, that eventually lead to a metastability of the gas-liquid transition below α = 1.2.

Side-of-onset of Parkinson's disease in relation to neuropsychological measures

BACKGROUND

Parkinson's disease (PD) usually emerges with a unilateral side-of-onset (left-onset: LOPD; right-onset: ROPD; Marinus & van Hilten, 2015) due to an asymmetrical degeneration of striatal dopaminergic neurons (Donnemiller et al., Brain, 135, 2012, 3348). This has led to a body of research exploring the cognitive, neuropsychological, and clinical differences between LOPD and ROPD (e.g., Verreyt et al., Neuropsychology Review, 21, 2011, 405).

METHODS

Thirty ROPD and 14 LOPD cases were drawn from a Boston clinic specializing in PD. Various cognitive and neuropsychological measures were used in an attempt to discover if there were indeed any differences between LOPD and ROPD in this cohort.

RESULTS

For LOPD, duration of illness was found to be significantly greater than that of ROPD. However, further testing was able to confirm that despite this difference, it was not the cause of the other significant differences found. Furthermore, this increased duration was consistent with a previous study (Munhoz et al., Parkinsonism and Related Disorders, 19, 2013, 77). Performance on the Digit Span Backward (DSB) was found to be significantly poorer in LOPD than ROPD, suggesting compromised executive function in LOPD. Additionally, LOPD had significantly greater anxiety on the DASS Anxiety scales than ROPD. However, unlike Foster et al (Cognitive and Behavioral Neurology, 23, 2010, 4), this increased anxiety could not account for the poorer performance on the DSB for LOPD. Finally, ROPD had significantly greater magical ideation than LOPD, which can be explained by the theory put forth by Brugger and Graves (European Archives of Psychiatry, 247, 1997, 55).

CONCLUSION

Clear and significant differences between LOPD and ROPD were found within our cohort. LOPD showed greater impairment of working memory, greater anxiety, and greater duration of illness-all independent of one another; whereas, those with ROPD had greater magical ideation, also independent of any other variables.

Projected Increase in Periprosthetic Joint Infections Secondary to Rise in Diabetes and Obesity

Total joint arthroplasties (TJAs) are projected to increase, along with increased complications like periprosthetic joint infections (PJIs). However, no study has projected TJAs secondary to PJI and how these relate to comorbidities in these patients. The NIS database was assessed from 1993 to 2000 to evaluate primary and revision TJAs, and projections were made until 2028. ICD-9 codes were used to identify patients with obesity, diabetes, and PJI. Rates of diabetes and adult obesity are predicted to increase for both genders, and patients receiving revision surgery for PJI are predicted to increase over time; males had higher rates than females. With an exponential increase of PJI secondary to diabetes and obesity, it is imperative that orthopedists intervene in these patients prior to TJA to decrease PJI's burden.

Cluster formation and phase separation in heteronuclear Janus dumbbells

We have recently investigated the phase behavior of model colloidal dumbbells constituted by two identical tangent hard spheres, with the first being surrounded by an attractive square-well interaction (Janus dumbbells, Munaó et al 2014 Soft Matter 10 5269). Here we extend our previous analysis by introducing in the model the size asymmetry of the hard-core diameters and study the enriched phase scenario thereby obtained. By employing standard Monte Carlo simulations we show that in such 'heteronuclear Janus dumbbells' a larger hard-sphere site promotes the formation of clusters, whereas in the opposite condition a gas-liquid phase separation takes place, with a narrow interval of intermediate asymmetries wherein the two phase behaviors may compete. In addition, some peculiar geometrical arrangements, such as lamellæ, are observed only around the perfectly symmetric case. A qualitative agreement is found with recent experimental results, where it is shown that the roughness of molecular surfaces in heterogeneous dimers leads to the formation of colloidal micelles.

Phase separation and self-assembly of colloidal dimers with tunable attractive strength: from symmetrical square-wells to Janus dumbbells

We numerically investigate colloidal dimers with asymmetric interaction strengths to study how the interplay between molecular geometry, excluded volume effects and attractive forces determines the overall phase behavior of such systems. Specifically, our model is constituted by two rigidly-connected tangent hard spheres interacting with other particles in the first instance via identical square-well attractions. Then, one of the square-well interactions is progressively weakened, until only the corresponding bare hard-core repulsion survives, giving rise to a "Janus dumbbell" model. We investigate structure, thermodynamics and phase behavior of the model by means of successive umbrella sampling and Monte Carlo simulations. In most of the cases, the system behaves as a standard simple fluid, characterized by a gas-liquid phase separation, for sufficiently low temperatures. In these conditions we observe a remarkable linear scaling of the critical temperature as a function of the interaction strength. But, as the interaction potential approaches the Janus dumbbell limit, we observe the spontaneous formation of self-assembled lamellar structures, preempting the gas-liquid phase separation. Comparison with previous studies allows us to pinpoint the role of the interaction range in controlling the onset of ordered structures and the competition between the formation of these structures and gas-liquid condensation.

Fibroma of the peroneus longus tendon sheath in a child: a case report

Tendon sheath fibromas are rare, benign soft-tissue tumours and usually involve tendons of the upper extremities, particularly the fingers. The most common presentation is a painless, slow-growing swelling. Tendon sheath fibromas are composed of dense fibrocollagenous stromas with scattered, spindle-shaped fibroblasts and narrow, slit-like vascular spaces. Ultrasonography and magnetic resonance imaging are useful diagnostic tools. We report on an 11-year-old boy with a fibroma involving the right peroneus longus tendon sheath.

Electroporation of cells using EM induction of ac fields by a magnetic stimulator

This paper describes a method of effectively electroporating mammalian cell membranes with pulsed alternating-current (ac) electric fields at field strengths of 30-160 kV m(-1). Although many in vivo electroporation protocols entail applying square wave or monotonically decreasing pulses via needles or electrode plates, relatively few have explored the use of pulsed ac fields. Following our previous study, which established the effectiveness of ac fields for electroporating cell membranes, a primary/secondary coil system was constructed to produce sufficiently strong electric fields by electromagnetic induction. The primary coil was formed from the applicator of an established transcranial magnetic stimulation (TMS) system, while the secondary coil was a purpose-built device of a design which could eventually be implanted into tissue. The effects of field strength, pulse interval and cumulative exposure time were investigated using microscopy and flow cytometry. Results from experiments on concentrated cell suspensions showed an optimized electroporation efficiency of around 50%, demonstrating that electroporation can be practicably achieved by inducing such pulsed ac fields. This finding confirms the possibility of a wide range of in vivo applications based on magnetically coupled ac electroporation.

Central cord syndrome in Ireland: the effect of age on clinical outcome

Central cord syndrome is an incomplete spinal cord injury first described by Schneider et al. (J Neurosurg 11:546-547, 1954). The typical neurological deficit is symmetrical incomplete quadriplegia affecting the upper more than the lower limbs; sensory impairment is variable and urinary retention is common. Records of all patients with acute traumatic central cord syndrome admitted to the National Spinal Injuries Unit from 1999 to 2007 were compiled from a prospectively collected computerized spinal database. Data recorded included patient demographic profile, mechanism of injury, initial neurological deficit, treatment instituted, complications of treatment, and final neurological status. A total of 50 patients with acute traumatic central cord syndrome were identified accounting for 6.2% of all admissions to the spinal injuries unit. There were 42 men and 8 women. The mean age was 56.1 years with a range of 41-88 years. We stratified patients according to age at injury to determine the effect of age on clinical outcome. There were 13 patients <50 years of age, 24 aged 50-70, and 13 aged >70 years. The mean follow-up time was 42.2 months. More than one-third of patients were intoxicated with alcohol at the time of the injury. Both upper and lower limb motor scores and total sensory scores improved in all age groups. Absolute and relative improvements were greatest in patients <50 years of age. Sphincter disturbance was documented in 42% of all the patients on admission. At follow up 12% of patients had residual disturbance. At final follow up none of the patients under 70 years of age had residual sphincter disturbance while 60% of those aged >70 years group had. Both of these results reached statistical significance. In conclusion, central cord syndrome is a common cause of acute traumatic neurological deficit, with alcohol intoxication being a common confounder at the time of injury. The clinical outcomes are significantly worse in patients aged 70 years or older.

Epidemiology of major paediatric trauma

In Europe injury is the leading cause of death in those aged between 1 and 14 years. In Ireland over 800,000 people are aged less than 14 years. There is currently no national trauma register to collect data on the morbidity and mortality associated with major trauma in the paediatric population in Ireland. We prospectively collected data on 153 patients admitted to our hospital with major trauma. There were 99 males and 54 females. The majority of patients were transported by ambulance (n= 138). Road traffic accidents (n=69) and thermal injuries (n=49) represented the majority of admissions. 68% (n=47) of the vehicle occupants in this study were either unrestrained or incorrectly restrained. Most patients (n=133) had an in patient stay of <50 days, with only 4 patients staying >100 days. 14 patients died. A paediatric trauma register as well as a level 1 paediatric trauma centre are required in Ireland.

Epidemiology of sporting and recreational injuries in a paediatric orthopaedic outpatients department

Knowledge of the number and type of injuries attending the paediatric orthopaedic outpatients is crucial in the future planning of any new paediatric hospital. We prospectively collected data on all new patients attending two paediatric orthopaedic out-patients departments, over a four month period. There were a total of 1,791 completed questionnaires. Sporting and recreational injuries represented 270% and 28% of the total attending, respectively. The new use of heelies represented 11% of the recreational injuries. The upper limb injuries represented 74% of the total, with the lower limb accounting for 25%. Treatment was nonoperative or operative. The number of patients, and the types of injuries presenting demonstrates the workload involved in diagnosing and treating these injuries. A total of 827 casts were applied. With almost half of those attending the clinic requiring a cast, the workload on the plaster technicians is substantial, and has implications for future service planning.

Detection of dimers of dimers of human leukocyte antigen (HLA)-DR on the surface of living cells by single-particle fluorescence imaging

The technique of single-particle fluorescence imaging was used to investigate the oligomeric state of MHC class II molecules on the surface of living cells. Cells transfected with human leukocyte antigen (HLA)-DR A and B genes were labeled at saturation with a univalent probe consisting of Fab coupled to R-phycoerythrin. Analysis of the intensities of fluorescent spots on the cell surface revealed the presence of single and double particles consistent with the simultaneous presence of HLA-DR heterodimers and dimers of dimers. The proportion of double particles was lower at 37 degrees C than at 22 degrees C, suggesting that the heterodimers and dimers of dimers exist in a temperature-dependent equilibrium. These results are discussed in the context of a possible role for HLA-DR dimers of dimers in T cell receptor-MHC interactions. The technique is validated by demonstrating that fluorescence imaging can distinguish between dimers and tetramers of human erythrocyte spectrin deposited from solution onto a solid substrate. The methodology will have broad applicability to investigation of the oligomeric state of immunological and other membrane-bound receptors in living cells.

Enhancement of photodynamic therapy in gastric cancer cells by removal of iron

BACKGROUND

Aminolaevulinic acid (ALA) is an endogenous substrate in the haem biosynthetic pathway. Protoporphyrin IX (PPIX), the immediate haem precursor in the pathway, has photoexcitable properties. Exogenous ALA has been used previously as a precursor agent in photodynamic therapy (PDT). Its main advantage is a short half-life and hence reduced incidence of skin photosensitivity. ALA can be toxic, however, causing, for example, transient increases in liver enzyme concentrations when given systemically and this may be dose related.

AIM

To assess whether accumulation of PPLX and ultimately the efficacy of PDT could be improved by modulating both ends of the haem biosynthetic pathway.

METHODS

Gastric cancer cells (MKN 28) were incubated with ALA (0-1000 mumolar) and desferrioxamine (0-800 mumolar) for 24 hours before exposure to argon-pumped dye laser (630 nm) at different energy levels (0-40 J/cm2). Cell viability was assessed by use of the methyl-tetrazolium (MTT) assay four hours after exposure to light.

RESULTS

Total PPIX accumulation increased linearly with increasing extracellular concentrations of ALA up to 1 mmolar (r = 0.973, p < 0.005). Adding 200 molar of desferrioxamine trebled PPIX accumulation over the same period of incubation. Cell viability after exposure to light decreased with low doses (0-30 mumolar) of desferrioxamine (r = 0.976, p = 0.024). However, higher doses of desferrioxamine (more than 40 molar) seemed to confer a protective effect against PDT.

CONCLUSION

PDT using ALA can be improved by removal of available iron with desferrioxamine. The reason for the protective effect of desferrioxamine seen at higher doses is not clear.

Two major classes in the M protein family in group A streptococci

The M protein family of molecules in the group A streptococcus comprises a number of cell surface proteins that interact with the immune system of the host. One of the proteins in this family is the IgA receptor Arp4, which has C repeats similar to those that characterize the known M proteins. The streptococcal strain expressing Arp4 also expresses a second immunoglobulin-binding protein, Mrp4, which is shown here to be encoded by a gene located immediately upstream of the gene for Arp4. In addition to binding IgG, Mrp4 also binds fibrinogen, a property ascribed to M proteins. DNA sequence analysis demonstrated that the Mrp4 protein indeed is a member of the M protein family, but it was unexpectedly found to have a type of repeat that is identical to the A repeat described for FcRA76, a partially sequenced streptococcal Fc receptor. Purified FcRA76 was shown to bind fibrinogen and IgG, like Mrp4. These data show that the known molecules in the M protein family can be divided into two classes, A and C, according to the type of repeat region found. Hybridization studies with a panel of clinical isolates indicate that many streptococcal strains express class A and class C proteins, whereas some strains express only class C proteins. Class A molecules show amino-terminal sequence variation, like class C molecules, which suggests that proteins of both classes are targets for the immune response.

Many group A streptococcal strains express two different immunoglobulin-binding proteins, encoded by closely linked genes: characterization of the proteins expressed by four strains of different M-type

Most group A streptococcal strains are able to bind immunoglobulin (Ig) in a non-immune manner, and the majority of these strains bind both IgA and IgG. Using molecular cloning and immunochemical techniques, we have purified and characterized the Ig Fc-receptors expressed by four such strains. Two of the strains express a novel type of receptor, designated protein Sir, which binds IgA and IgG of all subclasses, and therefore has broader reactivity than any Fc-receptor previously described. The other two strains express protein Arp, a receptor that binds IgA of both subclasses, and also binds polyclonal IgG weakly. Characterization of the weak IgG-binding ability of protein Arp shows that it binds only some monoclonal IgG proteins, in particular those of the IgG3 subclass. The four strains studied here were unexpectedly found to also express a second Ig-receptor, called protein Mrp, encoded by a gene closely linked to the gene for the first receptor. The Mrp protein does not bind IgA, but it binds IgG molecules of the IgG1, IgG2 and IgG4 subclasses, and it also binds fibrinogen. Binding of fibrinogen has been reported to be a characteristic property of streptococcal M proteins, which suggests that the Mrp protein may be an M protein that also binds Ig. Taken together, all available evidence now indicates that most strains of group A streptococci express two different Ig-binding proteins, encoded by closely linked genes.

High-affinity binding of the basement membrane proteins collagen type IV and laminin to the gastric pathogen Helicobacter pylori

The ability of 16 isolates of the human gastroduodenal pathogen Helicobacter pylori to bind 125I-radiolabelled tissue proteins was quantitated by liquid-phase assay. While capable of binding generally low levels of collagen types I and II, vitronectin, and fibronectin (average binding, 8%; highest binding, 23%), the various H. pylori isolates were good binders of the basement membrane proteins collagen type IV and laminin (average binding, 27%; highest binding, 60%). Campylobacter species tested bound lower levels of collagen type IV and laminin (average binding, 12%; highest binding, 17%). Trypsin and proteinase K treatment of H. pylori cells markedly reduced the binding of collagen type IV and laminin, as did heat treatment, suggesting that the binding of basement membrane proteins is mediated by bacterial surface proteins. Binding of both basement membrane proteins was rapid and saturable. 125I-collagen type IV binding to H. pylori 915 was inhibited by preincubation with unlabelled collagen type IV but was not inhibited by laminin or a number of other proteins. Once bound, radiolabelled collagen type IV but was not displaced by an excess of unlabelled collagen type IV, indicating that the binding interaction was of high affinity. Binding of laminin was partially reversible, and analysis in a solid-phase nonradiolabel assay showed that the interaction was of high affinity, with a Kd of 7.9 nM. This interaction was affected by salt, indicating the presence of a hydrophobic component in the ability of H. pylori to bind laminin.

Binding to collagen by Yersinia enterocolitica and Yersinia pseudotuberculosis: evidence for yopA-mediated and chromosomally encoded mechanisms

Binding of Yersinia enterocolitica and Yersinia pseudotuberculosis strains to type I, II, and IV collagens has been studied. Wild-type strains which harbored the 40- to 50-megadalton virulence plasmid specifically bound all three types of collagen. Curing of the virulence plasmid or Tn5 insertion in the yopA gene encoding the temperature-inducible outer membrane protein YOP1 abolished the binding of all three collagen types to Y. enterocolitica and type I and II collagens to Y. pseudotuberculosis. Full binding capacity was restored by introduction of the yopA gene into nonbinding Yersinia strains. Binding of type I, II, and IV collagens was expressed in Escherichia coli constructs harboring the yopA gene of either Y. enterocolitica or Y. pseudotuberculosis. The interaction of bacterial cells with type I collagen could be blocked by nonradiolabeled native collagens or denatured collagen but not with other serum and connective-tissue proteins. Unlabeled collagen could not displace bound radiolabeled collagen. The binding was inhibited by YOP1-specific polyclonal antibodies, in contrast to normal rabbit serum. The interaction was rapid and was quite resistant to heat treatment, to proteolytic enzymes, to various pHs in both acidic and alkaline ranges, and to the chaotropic agent urea. We propose that this newly identified interaction may be involved both in the first steps of the pathogenesis and in the complications of Yersinia infections affecting connective tissue.