Biomedical subjects
Publications and source records attributed to P Woo.
A case of scleroderma 'en coup de sabre' presenting with uveitis, predominantly posterior, and intractable grand mal seizures is described. The histopathology specimens and neuroradiology investigations reaffirm the clinical impression that inflammation is not solely confined to the skin in this form of linear scleroderma.
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A history of poor weight gain can often be elicited in young children with chronic upper airway obstruction resulting from adenotonsillar hypertrophy. A series of 41 consecutive children under 3 years of age, who underwent inpatient adenotonsillectomy, were reviewed for changes in weight and height. Thirty-seven patients had adequate long-term follow-up. Of these, many had dramatic improvements in growth after adenotonsillectomy. Indications for surgery in this group were recurrent infection in three patients (7%), unilateral tonsillar mass in one patient (3%), and upper airway obstruction in 37 patients (90%). A clear history of sleep apnea was elicited in 59%. At the time of surgery, 19 of 41 patients (46%) were of the fifth percentile or lower for age-corrected weight. The inpatient hospital stay averaged 3.2 days. The postoperative complication rate was 27%, with postoperative stridor as the most common complication. After surgery, 28 children (75%) showed a change to a higher percentile for weight. Twenty-four (65%) had percentile changes of 15% or more. This change is significant according to results of the Wilcoxon signed-rank test (p less than 0.001). We conclude that a relationship exists between improved growth rate and adenotonsillectomy in our study group. The rapid improvement in growth appears to be most obvious in children with upper airway obstruction resulting from adenotonsillar hypertrophy. Upper airway obstruction (including andenotonsillar hypertrophy) should be suspected as a possible cause in the workup of children with suboptimum growth.
Phonatory function can be reliably tested after vocal paralysis. After a review of 116 cases, 55 patients underwent objective testing. The clinical history of vocal ability and aspiration were found to be significantly correlated with measurements of phonatory mean flow rate (MFR), maximum phonation time (MPT), and maximum decibel output (SPL). A four-stage classification system, based on clinical and objective measurements, has been formulated. In stage I, measures of vocal parameters approached those of normals with MFR = 155 cc/sec, MPT = 12 sec, and SPL = 92 dB. Patients with stage IV disability have high MFR (480 cc/sec), but low MPTs (less than 3 sec) and low SPL values (76 dB). Factors such as sex, age, weight loss, and the presence of malignancy affect the degree of vocal function deficit. Post-therapy recordings indicated an improvement in vocal function by an increase in MPT and SPL, with a decrease in MFR. Measurements of MFR, PT, and SPL are good objective indicators available to the clinician. Functional staging can be applied to assessment and treatment of vocal cord paralysis.
CO2 laser-assisted myomectomy of the thyroarytenoid muscle (TA) was carried out through a thyroplasty approach in ten laryngeal specimens and the TA was examined histologically. Using the CO2 laser at super-pulsed mode, the TA can be cut or resected using 3-5 W of laser power. There is good control of the depth and extent of TA resection. Histologically, there is little evidence of collateral injury, with sparing of vital surrounding vocal structures. The use of CO2 laser for TA resection offers better access and surgical hemostasis in an otherwise difficult surgical field. Laser-assisted myomectomy may be a feasible alternative to current methods to treat spasmodic dysphonia.
A 16 year old girl with a two year history of systemic sclerosis developed left axillary vein thrombosis. Prolonged euglobulin clot lysis time, anti-endothelial cell antibodies, and raised von Willebrand factor antigen were shown.
Defects of the laryngeal framework after trauma, cancer, and thyroplasty have been reconstructed with mini-reconstruction plates. Six patients had miniplates used to repair the thyroid cartilage defect after type I thyroplasty to prevent lateralization of the Silastic implant; three patients had miniplates used after hemilaryngectomy to bridge the thyroid cartilage remnants, resulting in better deglutition after hemilaryngectomy; and three patients had miniplates used to repair laryngeal fractures. The plates were tolerated well by the patients; there were no major complications. Rigid fixation using miniplates for laryngeal reconstruction has unique advantages over the use of wires. It offers the advantages of rigid and immediate stabilization with the ability to bridge large defects. It can be an alternative to existing techniques of laryngeal reconstruction.
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Immunogenetic studies in the past decade have confirmed the theory of an association between one's immunogenetic background and the manifestation of several forms of juvenile chronic arthritis (JCA), in particular pauciarticular-onset JCA. Considerable work has been done at the serologic level to demonstrate disease association with the major histocompatibility Class II antigens in pauciarticular-onset JCA. The polygenic nature of JCA is best illustrated by the findings in this particularly well-defined clinical subgroup. Evidence is now emerging that analysis of the DNA sequence, the derived protein sequence, and the structure of Class II molecules will yield significant insight into the genetic predisposition to JCA.
Serum amyloid A protein (apo-SAA) is an acute-phase reactant and an apolipoprotein of high density lipoproteins (HDL). Six major isoforms of apo-SAA occur in humans (pI 6.0, 6.4, 7.0, 7.4, 7.5, 8.0). In this report we have rationalized the phenotypic expression of apo-SAA isoforms with published apo-SAA structures predicted from apo-SAA cDNA's pA1 and pSAA82 and the genomic DNA SAAg9. The six apo-SAA isoforms fall into three pairs, pI 6.0/6.4, 7.0/7.5, and 7.4/8.0, which are products of cDNA pA1, cDNA pSAA82, and genomic DNA SAAg9, respectively. The second of each isoform pair (i.e. pI 6.4, 7.5, and 8.0) is the "primary" product: a 104-residue peptide with the NH2-terminal sequence Arg-Ser-Phe-Phe. Each primary product is processed either to a major 103-residue peptide with the NH2-terminal sequence Ser-Phe-Phe or processed to a minor 102-residue product which results from the loss of both an Arg and a Ser residue from the NH2 termini. These "secondary" products have the lower pI values of 6.0, 7.0, and 7.4, respectively. The isoelectric points of the SAAg9 products were confirmed by expression of SAAg9 in transfected mouse L-cells. Both the pI 8.0 and 7.4 isoforms were present in cellular extracts, suggesting that post-translational modification of apo-SAA may occur intracellularly. However, the greater relative abundance of the pI 7.4 isoform extracellularly suggests that the major conversion may occur after secretion. Whereas the gene corresponding to the pA1 cDNA sequence does not show allelic variation, the segregation characteristics of the pI 7.0/7.5 and 7.4/8.0 isoform pairs amongst individuals suggests that these isoforms are the products of genes (with sequences corresponding to pSAA82 and SAAg9, respectively) which are allelic variants at a single locus distinct from that for the pI 6.0/6.4 isoform pair.
This investigation was initiated to provide data on the ultrastructural basis for neurologic age-related changes in laryngeal sensory function. In the present study, an animal model (female Wistar rats: age range: young [Y], 3 to 5 months; old [O], 25 months; and very old [VO], 29 to 30 months) was used to examine systematically changes in the internal branch of the superior laryngeal nerve with age using electron microscopic morphometric techniques. Total fiber counts, fiber populations (size categories), and mean fiber size for myelinated and unmyelinated fibers did not change with age. Qualitative changes were consistent with segmental demyelination and axonal degeneration in the older animals. There was also a significant age-related increase in the volume fraction of adaxonal Schwann cell cytoplasm (Y, 0.019; O, 0.041; and VO, 0.042). Ultrastructural correlates of intracellular support and axonal transport showed a significant decrease in the numerical density of neurofilaments (Y, 0.126/micron2; O, 0.073/micron2; and VO, 0.078/micron2) in the older animals, but no change in the numerical density of microtubules. Energy metabolism correlates in the form of mitochondrial volume fraction did not change with age. There was a significant increase in the volume fraction of the intrafascicular extracellular space (Y, 0.224; O, 0.271; and VO, 0.301), indicating a late, age-related change in the extracellular environment. These changes could lead to decreased conduction velocity or complete fiber dysfunction. A number of these changes resembled those of aged human peripheral nerves already examined.
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We have analyzed the 5'-flanking region of one of the genes coding for the human acute-phase protein, serum amyloid A (SAA). We found that SAA mRNA could be increased fivefold in transfected cells by treatment with phorbol 12-myristate 13-acetate (PMA). To analyze this observation further, we placed a 265-base-pair 5' SAA fragment upstream of the reporter chloramphenicol acetyltransferase (CAT) gene and transfected this construct into HeLa cells. PMA treatment of these transient transfectants resulted in increased CAT expression. Nuclear proteins from PMA-treated HeLa cells bound to this DNA fragment, and methylation interference analysis showed that the binding was specific to the sequence GGGACTTTCC (between -82 and -91), a sequence previously described by R. Sen and D. Baltimore (Cell 46:705-716, 1986) as the binding site for the nuclear factor NF kappa B. In a cotransfection competition experiment, we could abolish PMA-induced CAT activity by using cloned human immunodeficiency virus long-terminal-repeat DNA containing the NF kappa B-binding sequence. The same long-terminal-repeat DNA containing mutant NF kappa B-binding sequences (G. Nabel and D. Baltimore, Nature [London] 326:711-713, 1987) did not affect CAT expression, which suggested that binding by an NF kappa B-like factor is required for increased SAA transcription.
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Fifty head-injured patients who had tracheostomy were followed during rehabilitation by video fiberoptic laryngoscopy examination. Complications of aspiration (23/50), airway stenosis (13/50), and phonation dysfunction (16/24) were followed. Spontaneous resolution of aspiration may require a prolonged course. A majority of patients (37/50) had improvement and could be decannulated. Prognostic factors correlated to eventual decannulation included age, level on the Glasgow Coma Outcome Scale, and type of head injury. Those with poor neurologic improvement and glottic incompetence (13/50) are poor candidates for decannulation. Significant airway stenosis can involve both laryngeal and tracheal sites. Neurologic dysfunction may complicate the decannulation process after airway anatomy has been restored by surgery. Dysphonia resulting from intubation, peripheral laryngeal and nerve injury, or central laryngeal movement dysfunction are common. Preventive maintenance with ongoing evaluation can avoid airway crises such as aspiration pneumonia, hemoptysis, and innominate artery.
We have detected circulating IgG antibodies that bind with high affinity to human umbilical vein endothelial cells in 74% of patients with systemic lupus erythematosus (SLE), 30% of those with scleroderma and 28% of those with rheumatoid arthritis. IgG binding was F(ab) mediated, and did not involve immune complexes. Anti-endothelial IgG were apparently unrelated to other circulating autoantibodies, including anti-cardiolipin or antiDNA IgG. Bound IgG from SLE or scleroderma patients was displaced by IgG from certain unrelated patients whereas others were ineffective. Anti-endothelial cell IgG from all sera tested were adsorbed by human dermal fibroblasts; erythrocytes and leucocytes each adsorbed a fraction of the activity. Purified IgG did not induce complement-mediated cytotoxicity. We conclude that a discrete group of IgG antibodies is common in connective tissue disease patients, reacts predominantly with endothelial cells and dermal fibroblasts, and may be important in the pathogenesis of vascular damage.
The structure of a human serum amyloid A (SAA) genomic clone (SAAg9) has been analyzed and the nucleotide sequence of the coding regions is compared with that of the cDNA for apoSAA1. The leader and coding sequences of exons 2 and 3 are identical to SAA1. However, there are 10 nucleotide and 7 derived amino acid substitutions in exon 4. These changes are identical to the amino acid sequence of the amyloid protein associated with familial Mediterranean fever. In particular, the amino acid substitution (Thr to Phe) at residue 69 of SAA1 may have an important role in this type of hereditary amyloidosis. The genomic clone SAAg9 has been transfected into mouse L cells, and constitutive expression of human specific mRNA and protein were observed in stable transfected clones. The expression of both SAA mRNA and protein were increased by incubation of the transfected cells with purified human interleukin-1 (IL-1), both human and mouse recombinant IL-1, and recombinant human tumor necrosis factor alpha. The induction of SAA is pretranslational and is likely to be mediated by protein factor(s) since incubation with cycloheximide diminished IL-1-dependent increase in SAA mRNA.
A genetic marker of susceptibility to systemic amyloidosis has been identified. A DNA polymorphic site, 5' to the serum amyloid P component gene, has been found to be significantly associated with amyloidosis in juvenile arthritic patients. When genomic DNA was cut with the restriction enzyme MspI and probed with the cDNA for serum amyloid P component, homozygosity for the 5.6 kb restriction fragment length polymorphic (RFLP) band was absent in all 28 amyloid patients. Furthermore, the proportion who were homozygous for the 8.8 kb RFLP band was greater (p = 0.008) than that among 89 normal subjects. The distribution of this polymorphic site among 19 juvenile arthritic patients without amyloidosis was the same as that in the normal group. Thus the 8.8 kb RFLP band represents a genetic predisposition to reactive amyloidosis in juvenile arthritis and may apply to amyloidosis associated with more common inflammatory conditions.