The Transcription Factor YY-1 Is an Essential Regulator of T Follicular Helper Cell Differentiation

T follicular helper (TFH) cells are a specialized subset of CD4 T cells that deliver critical help signals to B cells for the production of high-affinity Abs. Understanding the genetic program regulating TFH differentiation is critical if one wants to manipulate TFH cells during vaccination. A large number of transcription factor (TFs) involved in the regulation of TFH differentiation have been characterized. However, there are likely additional unknown TFs required for this process. To identify new TFs, we screened a large short hairpin RNA library targeting 353 TFs in mice using an in vivo RNA interference screen. Yin Yang 1 (YY-1) was identified as a novel positive regulator of TFH differentiation. Ablation of YY-1 severely impaired TFH differentiation following acute viral infection and protein immunization. We found that the zinc fingers of YY-1 are critical to support TFH differentiation. Thus, we discovered a novel TF involved in the regulation of TFH cells.

A particulate saponin/TLR agonist vaccine adjuvant alters lymph flow and modulates adaptive immunity

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Effect of alanine supplementation on oxalate synthesis

The Primary Hyperoxalurias (PH) are rare disorders of metabolism leading to excessive endogenous synthesis of oxalate and recurring calcium oxalate kidney stones. Alanine glyoxylate aminotransferase (AGT), deficient in PH type 1, is a key enzyme in limiting glyoxylate oxidation to oxalate. The affinity of AGT for its co-substrate, alanine, is low suggesting that its metabolic activity could be sub-optimal in vivo. To test this hypothesis, we examined the effect of L-alanine supplementation on oxalate synthesis in cell culture and in mouse models of Primary Hyperoxaluria Type 1 (Agxt KO), Type 2 (Grhpr KO) and in wild-type mice. Our results demonstrated that increasing L-alanine in cells decreased synthesis of oxalate and increased viability of cells expressing GO and AGT when incubated with glycolate. In both wild type and Grhpr KO male and female mice, supplementation with 10% dietary L-alanine significantly decreased urinary oxalate excretion ~30% compared to baseline levels. This study demonstrates that increasing the availability of L-alanine can increase the metabolic efficiency of AGT and reduce oxalate synthesis.

Multifaceted Effects of Antigen Valency on B Cell Response Composition and Differentiation In Vivo

How antigen valency affects B cells in vivo during immune responses is not well understood. Here, using HIV immunogens with defined valencies ranging from 1 to 60, we investigated the role of antigen valency during different phases of B cell responses in vivo. Highly multimerized immunogens preferentially rapidly activated cognate B cells, with little affinity discrimination. This led to strong early induction of the transcription factors IRF4 (interferon regulatory factor 4) and Bcl6, driving both early extrafollicular plasma cell and germinal center responses, in a CD4⁺ T-cell-dependent manner, involving B cells with a broad range of affinities. Low-valency antigens induced smaller effector B cell responses, with preferential recruitment of high-affinity B cells. Thus, antigen valency has multifaceted effects on B cell responses and can dictate affinity thresholds and competitive landscapes for B cells in vivo, with implications for vaccine design.

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Antigen valency dictates the magnitude and composition of B cell responses

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High valency enables robust activation and effector differentiation of B cells

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Antigen valency alters breadth of B cell affinities recruited

Multiplanar phalangeal and metatarsal osteotomies for hallux rigidus

Many articles have been published on the various treatments of hallux rigidus/limitus but few, if any, have focused solely on the osteotomies performed in the treatment of this disorder and provided a thorough review of the literature and critique of the procedures. Here, we describe the most commonly used, most widely accepted, and most effective osteotomies in the treatment of hallux limitus/rigidus. Along with this discussion are figures and tables to make the information accessible and user friendly. Among the procedures discussed are Keller arthroplasty, Keller interpositional arthroplasty, Bonney-Kessel, Mayo-Stone, Regnauld, Youngswick, Watermann, Watermann-Green, tricorrectional metatarsal osteotomy, sagittal V, LADO (long-arm decompression osteotomy), Drago, Lambrinudi (plantarflexory closing base wedge osteotomy), sagittal Scarf/sagittal Z, and Weil/Mau/distal oblique osteotomy.

Stress fracture of the patella. Confirmation by triple-phase bone imaging

An athlete complained of chronic knee pain but had minimal findings on physical examination and initial equivocal radiographs. Subsequent tomograms of the knee suggested a patella stress fracture. Three-phase bone imaging confirmed a stress fracture of the inferior pole of the patella.

Scintigraphic demonstration of pectineus muscle avulsion injury

An exercise-related avulsion injury of the insertion of the pectineus muscle is described. The abnormality was detected on a 4-hour delayed bone scan. Symptomatic injuries of the adductor muscles are uncommon and are not to be confused scintigraphically with a stress fracture of the proximal femoral shaft.

Fracture-dislocation of the articular surface of the third metatarsal head

Fracture of the metatarsal head is uncommon, and reports are rare of isolated osteochondral fracture of the articular surface of the metatarsal head, as occurred in the 18-year-old man reported here. Good results were obtained with closed reduction by manipulation and traction, followed by cast immobilization for 6 weeks.

Spinal arthrodesis for severe spondylolisthesis in children and adolescents. A long-term follow-up study

The long-term results of spinal arthrodesis were evaluated in fourteen children and adolescents who had severe spondylolisthesis. Twelve patients had an in situ posterior arthrodesis and the other two had, in addition, open reduction. The two patients who had open reduction lost correction when the rods were removed. At long-term follow-up, which averaged 11.9 years, all patients had a solid fusion and their activities were unrestricted. Two patients were dissatisfied with the cosmetic result. No intraoperative or postoperative complications occurred in association with the in situ arthrodeses that were performed alone. Posterior in situ arthrodesis proved to be an effective, reliable, and safe treatment for severe spondylolisthesis.

The pes anserinus transfer. A long-term follow-up

We evaluated forty-eight patients (fifty knees) with pes anserinus transfer at an average of nine years after operation. There was a high incidence of anteromedial and anterolateral rotatory instability. The incidence (54 per cent) of significant roentgenographic changes at follow-up was also high. Although many patients were improved symptomatically after pes anserinus transfer, only nineteen patients (38 per cent) had no limitation of function.

A chronicle of injuries of an American intercollegiate football team

Many studies concerning the injuries occurring in high school and intercollegiate football have been reported, including those emphasizing the number and type of injuries, geographic distribution of injuries, and the rate of injury compared to position, conditioning, officiating, equipment, and type of playing surface. This report focuses on the individual player involved in a sports program for four or five years and emphasizes the statistical probability of that individual sustaining an injury during his playing career. Conclusions, drawn from statistics compiled at Memphis State University from 1975 through 1979, involved 265 athletes. These 265 athletes sustained 283 injuries during this period. Of these 283 injuries, 69% were mild, 20% were moderate, and 11% were severe. The knee was most often involved and suffered the most severe injuries. Ankle injuries accounted for the second highest incidence of injury, but these were primarily mild or moderate injuries. The defensive line, especially the defensive ends, received the greatest percentage of injuries. The probability of injury for the individual player was found to be 106.7% for a five-year participant, 99.1% for a four-year participant, and 46.6% for a one-year participant.