Altered response to and production of TGF-beta by B cells from autoimmune NZB mice

New Zealand Black (NZB) mice spontaneously develop immune dysfunction manifested as autoimmune hemolytic anemia and systemic lupus erythematosus. In later life, a subset of these mice develop clonal CD5+ B cell tumors analogous to human chronic lymphocytic leukemia (CLL). NZB disease is marked by B cell hyperactivity characterized by spontaneous immunoglobulin secretion and proliferation. Elimination of autoreactive lymphocytes by apoptosis is a vital mechanism to prevent expansion of self-reactive lymphocyte population. TGF-beta appears to be an important factor in normal and abnormal immune regulation and this cytokine may play a role in the development of chronic human B cell tumors. We asked whether the response to or production of TGF-beta by NZB B cells was aberrant and could contribute to disease development. In this study, we demonstrated that the apoptotic response to TGF-beta was increased in B cells from NZB mice compared to B cells from normal BALB/c mice. The increased apoptosis was related to endogenous activation and was possibly mediated through increased expression of the TGF-beta Type II receptor. Despite functional differences between CD5-negative B cells and CD5-positive B cells, TGF-beta induced apoptosis in both populations to a similar extent. NZB B cells also secrete increased active TGF-beta compared to BALB/c B cells. We suggest that the aberrant secretion of active TGF-beta and the increased response to the apoptotic effects of TGF-beta by NZB B cells may play a role in the disease process of these mice, perhaps attempting to limit the autoimmune phenomena, but possibly also contributing to generalized immunosuppression. We also suggest that the CD5(+) tumors in the NZB mouse may not be a fully appropriate model of human CLL, since CLL B cells are abnormally resistant to the apoptotic effects of TGF-beta.

Coordination Networks of 3,3'-Dicyanodiphenylacetylene and Silver(I) Salts: Structural Diversity through Changes in Ligand Conformation and Counterion

Coordination networks of 3,3'-dicyanodiphenylacetylene (3,3'-DCPA, 1) with silver(I) salts characterized by single-crystal X-ray analysis are described. Network topology is found to depend on both the counterion and solvent employed during crystallization. The conformation adopted by the ligand varies between planar cisoid and planar transoid. With silver(I) triflate (AgCF(3)SO(3)) in benzene, a sheet structure of composition [Ag(1)CF(3)SO(3)]C(6)H(6) (2) forms in which silver(I) is five-coordinate and bonds to two nitrogen atoms of distinct 3,3'-DCPA molecules, another silver(I) ion, and two oxygen atoms of the triflate ions. Changing the solvent to toluene produces an undulating sheet structure of composition [Ag(2)(1)(CF(3)SO(3))(2)] (3) in which silver(I) is six-coordinate, bonding to a ligand nitrogen atom, to four oxygen atoms of bridging triflate ions, and to a neighboring silver(I) ion. In both triflate structures, 3,3'-DCPA adopts a transoid conformation with respect to the positioning of the nitrile groups. With silver(I) hexafluorophosphate (AgPF(6)), silver(I) hexafluoroarsenate (AgAsF(6)), or silver(I) hexafluoroantimonate (AgSbF(6)), 2-fold interpenetrated sheet structures [Ag(1)(2)]XF(6) (X = P (4), As (5), or Sb (6)) are obtained in which 3,3'-DCPA coordinates to tetrahedral silver(I) ions in a cisoid conformation. In spite of the large difference in counterion size, minimal network deformation is observed among these systems. Interestingly, with silver(I) perchlorate hydrate (AgClO(4).xH(2)O, x approximately 1), 3,3'-DCPA coordinates in a transoid conformation to tetrahedral silver(I) ions to form the 8-fold interpenetrated diamondoid network [Ag(1)(2)]ClO(4).H(2)O (7). An analysis of the packing of these networks is provided, and the results are compared to complementary systems previously reported from our study of coordination networks of dinitriles and silver(I) salts.

Participatory ergonomics in a red meat packing plant. Part II: Case studies

Three ergonomics-related case studies are presented to demonstrate the problem-solving method used by two participatory ergonomics teams. The problem-solving method was adapted from principles related to quality management (e.g., participation, structure, a scientific approach, and decision by consensus). The first two steps of the problem-solving method were related to identification and evaluation of the problem; the latter three steps were related to solution development, implementation, and evaluation. The problem evaluation process included the collection of background, exposure, and effects data. Solution development following evaluation of the problem started with a brainstorming session, then discussion to select interventions by consensus. The format for presenting the case studies was intended to be concise and visual with the intent of effectively documenting the teams' problem-solving processes.

Concurrent diagnosis of chronic lymphocytic leukemia and myelodysplastic syndrome

An elderly patient is described with concurrent presentation of chronic lymphocytic leukemia and myelodysplastic syndrome, documented by clinical and hematological findings, flow cytometry and cytogenetics. The chromosome data suggested that these disorders developed as separate clones from two different hematopoietic precursor cells in this patient.

Chronic lymphocytic leukemia B cells are resistant to the apoptotic effects of transforming growth factor-beta

Chronic lymphocytic leukemia (CLL) is the most common leukemia of the western world and is characterized by a slowly progressing accumulation of clonal CD5+ B cells. Our laboratory has investigated the role of transforming growth factor-beta (TGF-beta) and interleukin-4 (IL-4) in the pathogenesis of B-cell expansion in CLL. In vitro addition of TGF-beta did not increase spontaneous apoptosis of B cells from most CLL patients, as determined using the TUNEL method, compared with a twofold increase observed in cultures of normal B cells. There was similar expression of TGF-beta type II receptors on both CLL B cells and normal B cells. In contrast to apoptosis, CLL B-cell proliferation was variably inhibited with addition of TGF-beta. In vitro addition of IL-4, previously reported to promote CLL B-cell survival, dramatically reduced spontaneous apoptosis of CLL B cells compared with normal B cells. CLL B-cell expression of IL-4 receptors was increased compared to normal B cells. Thus, our results show aberrant apoptotic responses of CLL B cells to TGF-beta and IL-4, perhaps contributing to the relative expansion of the neoplastic clone.

Solid-Phase Synthesis of Phenylacetylene Oligomers Utilizing a Novel 3-Propyl-3-(benzyl-supported) Triazene Linkage

Sequence-specific phenylacetylene oligomers consisting of functionalized monomers (hexyl benzoate, hexyl phenyl ether, benzonitrile, and tert-butylphenyl) are synthesized in gram quantities using solid-phase methods. Growing oligomers are attached to a divinylbenzene cross-linked polystyrene support by the 1-aryl-3-propyl-3-(benzyl-supported) triazene moiety. This linkage is obtained by reaction of arenediazonium tetrafluoroborate salts with a n-propylamino-modified Merrifield resin. Condensation strategies are described, producing oligomers with higher yields and simplified procedures compared to solution-phase methods. Terminal acetylene is protected with a trimethylsilyl group. After deprotection of the resin-bound terminal acetylene, an aryl iodide monomer or an aryl iodide-terminated oligomer is coupled to the supported oligomer using a palladium(0) catalyst. The cycle can be repeated to produce sequence-specific oligomers of varying length and functionality. The resulting oligomers are liberated from the polymer support by cleavage of the 1-aryl-3-propyl-3-(benzyl-supported) triazene group by reaction with iodomethane producing an aryl iodide.

Use of ESR for the detection of irradiated dates (Phoenix dactylifera L.)

One variety (Aple) of Libyan dry dates (Phoenix dactylifera L.) was irradiated in a 60Co source to absorbed doses of 0.8, 1.0, 1.5 and 2.0 kGy. Unirradiated date stone contains a radical with a single line g = 2.0045, feature A. Irradiation to a dose of 2.0 kGy (the recommended dose for fruits in U.K.) induces the formation of additional radicals with signals g = 1.9895 and 2.0159, feature C. The single line having g = 2.0045 decays in both unirradiated and irradiated samples whereas the additional signals g = 1.9895 and 2.0159 remain almost unchanged over a period of time 15 months stored at room temperature and 4 degrees C.

IL-12 stimulation but not B7 expression increases melanoma killing by patient cytotoxic T lymphocytes (CTL)

Recent studies have demonstrated that rodent tumour cells engineered to secrete a variety of cytokines, or to express foreign antigens, MHC molecules or co-stimulatory molecules, are rejected by syngeneic animals. These observations have led to the initiation of a number of clinical trials using genetically modified tumour cells, to attempt to stimulate a patient anti-tumour immune response. In this study, a protocol has been developed to test in vitro the specific cytotoxic anti-tumour response generated from melanoma patient lymphocytes. The results showed that IL-12 in combination with IL-2 enhanced the autologous anti-melanoma CTL response, whereas B7.1 antigen expression on tumour cells did not increase anti-melanoma CTL generation. This method could be used to design more appropriate genetically modified tumour vaccines.

Use of participatory ergonomics teams to address musculoskeletal hazards in the red meat packing industry

Participatory ergonomics teams from two departments of a pork slaughtering plant analyzed musculoskeletal hazards and proposed ergonomics solutions for several jobs in the plant. The jobs were targeted based on association with a large number of injuries, one or more particularly severe injuries, high workers' compensation expenses, and/or high turnover plus absence of obvious solutions to abate the hazards. The teams used a structured problem-solving method that was generally derived from principles associated with quality improvement processes. Workers performing the targeted jobs were involved in the problem-solving process, even if they were not members of the team. The effectiveness of each team was assessed and compared in terms of the number of problem jobs addressed and feedback from team members. One team addressed all nine of its targeted jobs; the other team addressed eight of 12 targeted jobs. Feedback from team members regarding their teams' methods and performance was generally favorable. The major obstacle to effective team functioning in this project was the scheduling of meetings. There were also some obstacles related to team leadership. Overall, this project demonstrated that the use of participatory ergonomics teams that rely on structured problem-solving methods are able to work effectively to address musculoskeletal hazards, especially related to the upper extremities, in the red meat packing industry.

A simplified method for the coordinate examination of apoptosis and surface phenotype of murine lymphocytes

Murine lymphocytes readily undergo spontaneous and glucocortocoid-induced apoptosis in vitro. It has been previously demonstrated that during apoptosis, many cell types including lymphocytes, enzymatically cleave their DNA, thus demonstrating a sub-G0 DNA peak when stained with propidium iodide and analyzed by flow cytometry. In a mixed population, it is often desirable to phenotypically identify distinct populations or subsets undergoing apoptosis, thus requiring multiparameter analysis of surface phenotype and DNA content. Paraformaldehyde fixation procedures, although common for surface evaluation, have not been extensively used in methods quantifying apoptosis. To measure apoptosis in a mixed lymphocyte population, we evaluated a gentle detergent permeabilization and paraformaldehyde fixation procedure combined with propidium iodide (PI) DNA staining, adapted from existing methods for cell cycle studies. With this method and rigorous gating techniques which we defined, we detected both apoptotic and debris fractions within the sub-G0 cell cycle region of a glucocortocoid-treated murine lymphocyte cell line. Using this cell line, WEHI 231.7, as a lymphocyte model, we developed a logical gating strategy to exclude debris from analysis. We further demonstrated that apoptosis in freshly isolated murine lymphocytes detected with paraformaldehyde fixation and PI staining was quantitatively comparable to PI staining with ethanol fixation, or nick translation labeling of DNA strand breaks (TUNEL). Finally, using fresh murine spleen cells, we demonstrated that paraformaldehyde fixation preserves surface protein staining, allowing multiparameter analysis of immunophenotype and apoptotic or cell cycle status in a mixed lymphocyte population. Thus, this method offers an inexpensive and technically simple alternative for assessing apoptosis and surface phenotype.

The neurocalometer: watershed in the evolution of a new profession

The Neurocalometer and its companion devices opened the way for a Pandora's box of instruments that often beguiled the chiropractor. Straight Palmerites were disheartened and confused by B.J.'s emphasis on machines; the definition of "pure" chiropractic was blurred. Some tried to recapture an ultrastraight chiropractic by following D.D.'s admonition that no electrical appliance should enter the adjusting room, while many with mixer tendencies moved toward pan-therapy, choosing from an array of instruments parading before them. Determining the efficacy of any particular one presented a daunting task and helped flame the fires of schism.

Expression and physiologic significance of Kit ligand and stem cell tyrosine kinase-1 receptor ligand in normal human CD34+, c-Kit+ marrow cells

To determine the potential role of autocrine growth factor production in regulating primitive human hematopoietic cell development, we examined highly purified CD34+, c-Kit+ marrow mononuclear cells for expression of c-Kit ligand (KL) and stem cell tyrosine kinase 1 (stk1) ligand (STK1-L). Normal marrow mononuclear cells coexpressing CD34 and c-Kit were isolated by a combination of immunomagnetic bead isolation and fluorescence-activated cell sorting. Purified cells were then screened for expression of KL and stk1-L mRNA using a sensitive reverse transcription-polymerase chain reaction method. Using this approach, expression of both cytokine genes at the mRNA level was found in this highly enriched cell population. We then examined the functional significance of these mRNAs by inhibiting their expression with antisense (AS) oligodeoxynucleotides (ODN). In comparison to untreated or control ODN treated cells, inhibition of KL led to a 70% and 89% inhibition in burst-forming unit-erythroid (BFU-E) and colony-forming unit-Mix (CFU-Mix) colonies but had no significant effect on CFU-granulocyte-macrophage (CFU-GM) cloning efficiency. In contrast, inhibition of STK1-L alone had no effect on colony formation. However, when STK1-L AS ODN was combined with KL AS ODN, additive inhibition of CFU-GM and CFU-MIX but not of BFU-E colonies was observed. These findings, along with those of our previous studies showing inhibition of primitive hematopoietic cell growth with antisense ODN directed towards the stk1 receptor, suggest the possibility that both receptor/ligand axes regulate primitive hematopoietic cell growth via an autocrine growth loop.

Clinical heterogeneity reflects biologic diversity in chronic lymphocytic leukemia

As the incidence of B cell chronic lymphocytic leukemia increases in an aging population, it becomes more important to re-evaluate our understanding of the disease process and current therapy. Previous treatment strategies have been, for the most part, unsuccessful in prolonging survival and thus new approaches are needed. More intense cellular and molecular research on the biologic diversity of this neoplasm will further our understanding of the causes of clinical heterogeneity and refine our ability to predict progression. New approaches, based on alterations of neoplastic cell growth by cytokines or chemotherapeutic agents, may enable clinicians to 'customize' individual treatments based on the stages of CLL B cell differentiation and our understanding of factors involved in the regulation of apoptosis and proliferation at those stages. Taken together, these efforts should ultimately yield much new information that will lead to reduced morbidity and mortality in B-CLL, the most common form of human leukemia.

Reduced surface expression of transforming growth factor beta receptor type II in mitogen-activated T cells from Sézary patients

Sézary syndrome (SzS), the leukemic form of cutaneous T-cell lymphoma, is characterized by clonal proliferation of CD4+ T cells and immune dysfunctions, raising the possibility of cytokine-related abnormalities. We previously described a decreased response to the growth-inhibitory effects of transforming growth factor type beta (TGF-beta) in SzS T cells accompanied by apparent loss of surface type II TGF-beta receptor (TGF beta RII). To specifically determine if defects exist in TGF beta RII protein expression and/or transport in SzS patients, we developed a sensitive flow cytometric method to detect TGF beta RII on the surface and intracellularly in the CD4+ T cells. Our results indicate that unlike normal CD4+ T cells, CD4+ T cells from 9 of 12 SzS patients expressed little, if any, surface TGF beta RII in response to mitogen stimulation. At the intracellular level, however, pools of TGF beta RII were comparable to those in normal CD4+ T cells. This indicates that defective trafficking of this inhibitory cytokine receptor may contribute significantly to the development of this disease.

As ever, B.J.": The Palmer-Stoke correspondence of 1926-1952

John H. Stoke was a 1920 graduate of the Palmer School and a loyalist among the admirers of B.J. Palmer during the turbulent 1920s in which Palmer leadership was questioned and the Neurocalometer debacle had eroded his following. Stoke, however, was a critical B.J. advocate, and engaged in sometimes detailed analysis of Palmer-Stoke correspondence and the issues which confronted the profession in those difficult times in the early years of this century.

The Strain Index: a proposed method to analyze jobs for risk of distal upper extremity disorders

Based on existing knowledge and theory of the physiology, biomechanics, and epidemiology of distal upper extremity disorders, a semiquantitative job analysis methodology was developed. The methodology involves the measurement or estimation of six task variables (intensity of exertion, duration of exertion per cycle, efforts per minute, wrist posture, speed of exertion, and duration of task per day); assignment of an ordinal rating for each variable according to exposure data; then assignment of a multiplier value for each variable. The Strain Index is the product of these six multipliers. Preliminary testing suggests that the methodology accurately identifies jobs associated with distal upper extremity disorders versus jobs that are not; however, large-scale studies are needed to validate and update the proposed methodology.

Construction of bacteriophage expressing mouse monoclonal Fab fragments directed against the human MN glycophorin blood group antigens

BACKGROUND

The MN human blood group antigens are complex glycopeptide antigens at the amino terminus of glycophorin A. Many different mouse monoclonal antibodies to these antigens have been produced and characterized. The construction of combinatorial immunoglobulin libraries displaying antibody Fab fragments on the surface of bacteriophage (Fab-phage) represents a novel approach for developing monoclonal reagents, for exploring the diversity of the immune response to specific antigens, and for understanding the molecular basis of the interaction of an antibody with its antigen. However, it is necessary to determine whether Fab fragments displayed on bacteriophage surfaces retain immunologic characteristics similar to the intact antibodies.

STUDY DESIGN AND METHODS

Fab-phage were constructed from three anti-N (AH7, N61, and N92) and two anti-M (425/2B and M2A1) murine hybridomas. The Fab-phage and parental hybridomas were compared by enzyme-linked immunosorbent assay, Western blotting, and flow cytometry.

RESULTS

In each case, the Fab-phage and its parental hybridoma antibody had similar immunologic characteristics. In particular, their dependence on the pH of the buffer and on sialylation of the target antigen was similar.

CONCLUSION

These results suggest that Fab-phage may provide novel reagents with applications in immunohematology and may be useful in the study of the immune response to human blood group antigens.

Analysis of hydrocarbon dendrimers by laser desorption time-of-flight and fourier transform mass spectrometry

The first mass spectrometric analysis of a new class of hydrocarbon dendrimers that result from a convergent synthetic approach is reported. Molecular weights of a series of phenylacetylene dendrimers (715 to 14776 u MW) are characterized by ultraviolet matrix-assisted laser desorption (MALDltime-of-flight (TOF) mass spectrometry, direct and silver chemical ionization infrared laser desorption Fourier transform mass spectrometry @I'MSl, and ultraviolet matrix-assisted laser desorption silver chemical ionization Fourier transform mass spectromeby. New matrices and techniques were developed to facilitate analysis of the dendrimers. Mass measurement accuracies between 10 and 25 ppm are obtained for molecular ion species of the five dendrimers analyzed. Laser desorption time-of-flight and FI'MS techniques are shown to be complementary, with FTMS providing high mass resolution (27,000-67,000 resolving power) and accuracy for lower mass dendrimers (10-14 ppm) and MALD TOF yielding the highest resolution (1100 resolving power) and accuracy (25 ppm) for the largest dendrimer. These results are consistent with proposed empirical formulas.

Upper extremity disorders in a pork processing plant: relationships between job risk factors and morbidity

Thirty-two jobs at a pork processing plant were semi-quantitatively analyzed in terms of their ergonomic characteristics, then classified as "hazardous" or "safe" in terms of potential risk for elbow or hand/wrist disorders. The spectrum, number, and incidence of such disorders occurring during the preceding 20 months were then compared to the job analyses and hazard classifications. There were 104 disorders associated with 15 job categories. The disorders included epicondylitis (24), nonspecific hand/wrist pain (41), carpal tunnel syndrome (CTS) (21), trigger finger (12), trigger thumb (3), and De-Quervain's tenosynovitis (3). The strength demands of the jobs associated with morbidity were significantly greater than those of jobs without morbidity. Differences in wrist posture were less significant. Type of grasp and repetitiveness were not significantly different. Practically all morbidity (96%) was associated with the hazardous job categories and occurred with a characteristic pattern of co-morbidity. The hazard classification scheme correctly predicted risk of upper extremity morbidity for 13 (87%) of the 15 job categories associated with morbidity and correctly predicted a lack of risk of morbidity for 16 (94%) of the 17 job categories not associated with morbidity. Significantly elevated relative risks were observed for any upper extremity disorder (11.4), any disorder excluding CTS (39.4), all specific disorders (6.9), and all specific disorders excluding CTS (19.4). The relative risk for CTS was 2.8 and not statistically significant. The results of this study provide additional epidemiological evidence that upper extremity musculotendinous disorders and some cases of CTS may be causally associated with work. The exertional demands of a task best explained the occurrence of morbidity.

Meperidine for patient-controlled analgesia after cesarean section. Intravenous versus epidural administration

BACKGROUND

Although meperidine has been used for patient-controlled analgesia both intravenously (PCIA) and epidurally (PCEA), these routes have not been compared, and many studies have suggested that there is no advantage to the epidural route for administration of lipophilic opioids.

METHODS

A randomized, double-blind, crossover study was conducted for 24 h after cesarean section to compare the analgesic efficacy, side effects, patient satisfaction, drug use, and plasma drug concentrations with meperidine administered either as PCIA or as PCEA. Two groups, stratified for time of cesarean section during epidural anesthesia, postoperatively received either PCEA (group 1) or PCIA (group 2) with identical variables for 12 h before crossing to the other route for an additional 12 h.

RESULTS

Results from 45 patients showed a similar speed of analgesic onset but, subsequently, significantly lower pain scores both at rest and with coughing in those receiving PCEA (P = 0.0001). Nausea and pruritus scores did not differ between the groups in the first 12 h postoperatively, but sedation scores were significantly higher with PCIA (P = 0.0001). Patient satisfaction scores and preference significantly favored PCEA (P = 0.0001), with almost 90% of participants preferring the epidural route. Meperidine use was reduced approximately 50% with PCEA (P = 0.0001), and plasma meperidine and normeperidine concentrations were significantly lower (P = 0.0001).

CONCLUSIONS

We conclude that after cesarean section, PCEA with meperidine produces high-quality pain relief with few side effects and has significant advantages over PCIA meperidine. With the caveat that neonatal effects in breast-feeding mothers have yet to be evaluated, it can be highly recommended in this population.

Richter's syndrome associated with loss of response to transforming growth factor-beta

A patient with chronic lymphocytic leukemia developed a large cell lymphoma apparently derived from the same neoplastic B-cell clone (Richter's syndrome). At the same time, mitogen-stimulated proliferation of the patient's circulating leukemic B-cells was no longer inhibited by the regulatory cytokine transforming growth factor-beta (TGF-beta), suggesting that such loss of inhibition might be contributing to the clinical and biological progression of the disease.

Transforming growth factor-beta inhibits human T-cell proliferation through multiple targets

This study investigates further the inhibitory effects of transforming growth factor-beta (TGF-beta) on human T-lymphocyte responses to mitogenic stimulation. T cells were stimulated either with mitogenic concentrations of PHA or with submitogenic concentrations of Con A followed by the addition of IL-2. DNA synthesis ([3H]thymidine incorporation) in both systems was inhibited by 60-69% in the presence of TGF-beta, with maximal reduction occurring on days 4 and 5 of culture. Cell surface expression of transferrin receptor (TfR) and IL-2 receptor-alpha (p55) were inhibited by 20-80% in the Con A/rIL-2 system and 20-45% in the PHA system in the presence of TGF-beta. In addition, mitogen-induced up-regulation of TfR and IL-2R mRNA levels were inhibited by TGF-beta. Finally, we investigated the effect of TGF-beta on the assembly of clathrin monomers into assembled coated pits and vesicles, and essential step in TfR and IL-2R alpha turnover. Stimulation of T cells using either mitogen system resulted in an increase in the level of assembled clathrin, which was almost completely inhibited by TGF-beta. These findings suggest that TGF-beta may act at several sites in mitogen-mediated proliferative pathways to contribute to the inhibition of T-cell proliferation.

Variable region gene analysis of an isotype-switched (IgA) variant of chronic lymphocytic leukemia

Chronic lymphocytic leukemia of B-cell origin (B-CLL) is generally thought to arise by neoplastic transformation of B lymphocytes, which express CD5 and have features of an early stage of B-cell differentiation. To study isotype-switched B-CLL as a potentially more differentiated variant, we performed genetic and functional immunoglobulin (Ig) gene analysis in two cases of CD5+ B-CLL in which the peripheral blood mononuclear cells (PBMC) secreted predominantly IgA (CLL-249) or IgG (CLL-412) when stimulated with pokeweed mitogen in vitro. By cDNA sequencing and by studies of CLL-heterohybridomas, CLL-249 expresses the heavy chain constant region C alpha as anticipated, while CLL-412 expresses C mu, not C gamma. In CLL-249, the expressed VH gene is 98% homologous to VH26, a germline VH3 gene that occurs frequently in the fetal repertoire, and which has been associated with anti-DNA specificity. The VL gene of CLL-249 is a lambda VL gene for which the germline sequence is not known. In CLL-412, the VH gene is 100% homologous to the VH1 gene of a published anti-DNA antibody (21/28), and is probably a germline gene sequence; the VL gene is 100% homologous to 15AVKI, also a germline gene. The supernatant antibody of the CLL-412 heterohybridoma is an IgM-kappa, which reacts with ssDNA and cardiolipin. The CLL-249 heterohybridoma secreted IgA-lambda, which bound none of the antigens tested, a finding that may be related to amino acid differences from the probable germline V genes. The demonstration of an in vivo isotype-switched variant, such as CLL-249, suggests that B-CLL may be a heterogeneous group of clonal disorders, of which less common variants may have features of more differentiated B-cell stages, such as isotype switching.

Prevention strategies and the low back in industry

Several different approaches have been tried in industry to prevent low-back injuries. The scientific literature shows that only job-specific strength testing and ergonomic job design are partially effective in preventing low-back injuries. Job-specific strength testing is supported as a means of identifying high-risk workers who need to perform manual materials handling. However, this approach should be carefully validated for its effectiveness before it is used as a form of selection procedure. At present, ergonomic job design offers the most potential for preventing disabling low-back injuries and other musculoskeletal injuries. Quantitative and objective methods (such as NIOSH guidelines, biomechanical models, energy expenditure, and strength data) are available to analyze a given job and to determine the relative risk of an injury.

Function, structure, and responses of components of the muscle-tendon unit

A "muscle-tendon unit" is a composite structure that includes muscle, tendon, myotendon junctions, tendon sheaths, and tendon-bone junctions. Each component is unique in its structure, function, response to strain, and associated clinical disorders (usually called "tendinitis"). Tendinitis implies localized tenderness in the distribution of a muscle-tendon unit to palpation, passive stretching, or active contraction. A variety of distinct clinical entities associated with the various components of the muscle-tendon unit are usually grouped together under the term "tendinitis," although each has unique characteristics and etiologic factors. Most have short latencies and favorable prognoses with appropriate clinical management, and most also bear some direct relationship to biomechanical factors, such as compression or strain, as well as to work organizational factors, particularly unaccustomed work.

Carpal tunnel syndrome

Despite numerous publications in the literature, there is still a significant deficit of knowledge regarding carpal tunnel syndrome and its relationship to work. This chapter reviews a variety of observations from these studies. Epidemiologic studies have been mostly cross-sectional surveys using clinical criteria (symptoms and physical findings) as a basis for case definition, but these exposure assessments cannot discriminate between work-related and non-work-related cases of carpal tunnel syndrome. These studies do reveal a fairly consistent pattern of observations regarding the spectrum and relative frequency of upper extremity morbidity among jobs believed to be hazardous. Carpal tunnel syndrome, however, is but one of these disorders and is not the most common one. Historical perspectives, anatomic pathology, pathophysiology, theories of pathogenesis, epidemiologic observations, associations with exposure, and current issues are discussed.

Epidemiology of low-back pain in industry

Low-back pain and back injuries are of such a complex nature that any one criterion cannot be applied by itself to give a valid assessment of the risk associated with manual materials-handling jobs. There is no question that low-back pain is an extremely significant cause of disability and has a major socioeconomic impact, but many different personal and job factors are associated with the incidence and prevalence of these complaints. There is a need for ongoing systematic investigations of the multiple risk factors that may be causally related to low-back pain and may possibly be amendable to preventive interventions. Knowledge of workplace and individual risk factors is far from complete. Prospective studies are needed so that factors contributing to the development of low-back pain can be separated from factors resulting from low-back pain. It is difficult to relate low-back pain to the workplace because it occurs quite often in workers employed in sedentary occupations. However, incidence, severity, and disability are all related to the physical demands of the job. In this regard, jobs involving lifting, lowering, pushing, pulling, carrying, and holding; body movements such as frequent bending, twisting, and sudden movements; and working in bent-over postures appear to have a significant potential for producing low-back pain. A combination of lifting, bending, and twisting appears to be most hazardous. It is concluded that lifting heavy loads contributes to increased frequency and severity rates for low-back pain. This is true regardless of whether the lifting is performed over a short period or throughout the day and whether it is performed a few times per day of repetitively. If, however, such lifting is performed repetitively, the medical hazard extends beyond low-back problems to other musculoskeletal strain and sprain injuries and to fatigue-related injuries, particularly for weaker workers. In this latter regard, gender, age, anthropometry, and previous history of back pain are known to modify these risks for populations of workers. The inherent variability between workers and within any worker over time precludes the use of such factors to assign risk to any particular individual.