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We have prepared affinity-purified rabbit polyclonal antibodies to the near-C-terminal peptides of human monocarboxylate transporters (MCTs) 1, 2, and 4 coupled to keyhole limpet hemocyanin. Each antiserum reacted only with its specific peptide antigen and gave a distinct molecular weight band (blocked by preincubation with antigen) after chemiluminescence reaction on Western blots from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of tissue membrane proteins. Densitometry showed distinctive expression patterns for each MCT in a panel of 15 frozen human tissues, with the distribution of MCT1 >>MCT2>MCT4. Fluorescence microscopy of unfixed skeletal muscle using fluorescein-conjugated secondary antibody was correlated with reverse adenosine triphosphatase (ATPase) stained sequential sections to identify fiber-type localization. MCT1 expression was high in the sarcolemma of type 1 fibers, modest to low in type 2a fibers, and almost absent in type 2b fibers. In contrast, MCT4 expression was low to absent in the membrane of most type 1 fibers, but high in most 2a and in all 2b fibers, favoring the view that their high lactate levels during work may be channeled in part to neighboring type 1 (and perhaps 2a) fibers for oxidation, thereby delaying fatigue. MCT2 expression was limited to the sarcolemma of a type 1 fiber subset, which varied from <5 to 40%, depending on the specific muscle under study. Quantitative chemiluminescent densitometry of 10 muscle biopsies for their MCT2 and MCT4 content, each normalized to MCT1, confirmed the unique variation of MCT2 expression with biopsy site. The application of these antibodies should add to the understanding of motor unit physiology, and may contribute to the muscle-biopsy assessment of low-level denervation.

We fractionated leukocytes from three donors into >90% pure samples of granulocytes, lymphocytes, and monocytes and tested them for transcriptional and translational expression of three physiologically-proven lactate transporters, monocarboxylate transporter 1(MCT1), MCT2, and MCT4, using RT-PCR and affinity-purified rabbit antibody (Ab) to the C-terminal segment of each human MCT. Transcripts of all three MCTs were identified in each leukocyte fraction by RT-PCR and proven by sequencing of fragments extracted after isolation on agarose gels. Transporter protein of the appropriate size was demonstrated for each of the monocarboxylate transporters MCTs in lymphocytes and monocytes by Western blot, while lower-molecular-weight bands were found in granulocytes and are presumed to be degraded forms, because they were blocked by antibody-antigen (Ab-Ag) preincubation. IHC demonstrated all three MCTs in methanol-fixed droplets of all three leukocyte fractions; stain was abolished on omission of the primary Ab. Plasmalemmal staining occurred with all MCTs in all leukocyte fractions. Because the K(m) for lactate increases approximately fivefold at each step, with MCT2<1<4, leukocytes must use the full range of lactate binding to survive in acidic and hypoxic environments. Except for MCT4 in lymphocytes, all the MCTs also stained leukocyte cytoplasm, often with distinct granularity. Nuclear membrane staining was also seen with MCT1 and MCT2, while platelet plasmalemma stained only with MCT2.

SIGNIFICANCE:This study reports prevalence data combined independently for accommodative dysfunction, convergence insufficiency, visual field loss, and visual acuity loss in patients with traumatic brain injury in the absence of eye injury. OBJECTIVE:The objective of this study was to conduct a systematic review and meta-analysis to determine the prevalence rates of accommodative dysfunction, convergence insufficiency, visual field loss, and visual acuity loss in TBI patients without concomitant eye injury.

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