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Biomedical subjects

J Khan

Publications and source records attributed to J Khan.

At least 55 records · Page 3Linked to original sources
PubMed1998

3-Nitrotyrosine in the proteins of human plasma determined by an ELISA method.

The modification of tyrosine residues in proteins to 3-nitrotyrosine by peroxynitrite or other potential nitrating agents has been detected in biological systems that are subject to oxidative stress. A convenient semi-quantitative method has been developed to assay nitrated proteins in biological fluids and homogenates using a competitive ELISA developed in our laboratory. This assay selectivity detected 3-nitro-l-tyrosine residues in a variety of peroxynitrite-treated proteins (BSA, human serum albumin (HSA), alpha1-antiprotease inhibitor, pepsinogen and fibrinogen) and also in a nitrated peptide, but had a low affinity for free 3-nitro-L-tyrosine and 3-chloro-L-tyrosine. The IC50 values for the inhibition of antibody binding by different nitrated proteins were in the range 5-100 nM, suggesting that the antibody discriminated between nitrotyrosine residues in different environments. The presence of nitrotyrosine in plasma proteins was detected by Western blot analysis and quantified by the ELISA. A concentration of 0. 12+/-0.01 microM nitro-BSA equivalents was measured in the proteins of normal plasma which was increased in peroxynitrite-treated plasma and was elevated in inflammatory conditions. HSA and low-density lipoprotein (LDL) isolated from plasma contained 0.085+/-0.04 and 0. 03+/-0.006 nmol nitro-BSA equivalents/mg protein, respectively. Comparison of the level of nitration in peroxynitrite-treated HSA and LDL in the presence and absence of plasma indicates that nitration and presumably oxidation is inhibited by plasma antioxidants. The presence of nitrotyrosine in LDL is consistent with previous reports implicating peroxynitrite in the oxidative modification of lipoproteins and the presence of a low concentration of oxidized LDL in the blood.

Adult↗
PubMed1998

Detection of gains and losses in 18 meningiomas by comparative genomic hybridization.

Comparative genomic hybridization (CGH) was used to examine gains and losses in 18 meningioma tumors that had been previously analyzed for loss of heterozygosity (LOH) at 22q12. Partial or complete losses were seen by CGH in only 9 of 18 cases on chromosome 22. This compares with 11 of 18 losses of single or more loci by LOH. The discrepancy in these results in probably explained by the increased sensitivity of LOH by using microsatellite markers that are able to detect small deletions, whereas losses on the order of 10-15 megabases are required for confident identification by CGH. There was no consistent pattern of gains or losses by CGH, including those tumors that lacked LOH at 22q12. In one tumor of interest in which CGH and LOH studies failed to demonstrate loss on chromosome 22, CGH identified an area of amplification at 17q22-23.

Chromosome Deletion↗
PubMed1998

Zinc deficiency enhances interleukin-1alpha-induced metallothionein-1 expression in rats.

This study investigated whether interleukin-1alpha-induced metallothionein gene expression is affected by zinc deficiency. Weaning male rats were fed a zinc-deficient (ZD) diet (2 mg zinc/kg) or a zinc-supplemented diet [50.8 mg zinc/kg; controls for the diet included pair-fed (PF) and ad libitum consumption groups (AL)] for 4 wk. All rats except those that served as controls for interleukin-1alpha administration, (injected with vehicle and killed at 0 h) were then injected subcutaneously with interleukin-1alpha (2 x 10(7) units/kg body wt) and killed at 3, 6, 12, 24 and 72 h after the injection. Compared with AL and/or PF rats, zinc depletion significantly reduced zinc concentrations in plasma and liver but not in kidney or intestine, and significantly reduced hepatic, renal, and intestinal metallothionein-1 mRNA levels analyzed by competitive reverse transcription-polymerase chain reaction (RT-PCR). Interleukin-1alpha injection reduced plasma zinc concentration and enhanced liver zinc concentration, but did not affect zinc levels in kidney or intestine. Metallothionein-1 mRNA was significantly elevated by interleukin-1alpha in liver, kidney and intestine of all groups; the levels in liver and kidney of ZD rats 6 h after the injection were significantly higher than those of AL or PF rats. Liver metallothionein protein levels were enhanced after interleukin-1alpha injection in both AL and ZD rats. Semiquantitative RT-PCR revealed significantly higher hepatic levels of interleukin-1 receptor type-I mRNA in ZD rats than in AL and PF rats but no differences in renal or intestinal tissues among groups before interleukin-1alpha challenge. In conclusion, zinc deficiency induces upregulation of metallothionein-1 gene expression in response to interleukin-1alpha challenge in rats.

Animals↗
PubMed1997

Correlation of histologic subtypes of primary basal cell carcinoma and number of Mohs stages required to achieve a tumor-free plane.

BACKGROUND: Certain histologic subtypes of basal cell carcinoma (BCC) behave more aggressively and require more aggressive treatment. OBJECTIVE: The aim of this study was to see whether certain subtypes of BCC require more Mohs stages to achieve tumor-free margins. METHODS: A retrospective study of 342 primary BCCs treated with Mohs micrographic surgery (MMS) was performed identifying the histologic subtype of BCC present and the number of stages required to clear the tumor. RESULTS: The aggressive subtypes (infiltrative, morpheaform, micronodular, and mixed) were most frequently found when high numbers of Mohs stages were required for cure. CONCLUSION: The more aggressive subtypes of BCC require more MMS stages to achieve tumor-free margins, which is consistent with the concept that these subtypes usually require more aggressive treatment from the start.

Aged↗
PubMed1997

Circulating anti-(xanthine oxidoreductase) antibodies in healthy human adults.

Levels of free anti-(xanthine oxidoreductase) (XOR) antibodies in the serum of normal healthy human subjects were determined, using both human and bovine enzyme as antigen, in an enzyme-linked immunosorbent assay (ELISA). Levels of IgM class anti-(human XOR) antibodies were found to be particularly high (mean values representing approximately 3% of total IgM) and to be significantly higher than levels of IgM anti-(bovine XOR) antibodies, indicating that endogenous XOR, rather than ingested bovine milk XOR, is the immunogen. IgM anti-XOR antibody levels were significantly higher in women under 50 years than in age-matched men, or in older women. Levels of IgG class anti-XOR antibodies were much lower and showed no correlation with gender or age. Affinity-purified anti-(human XOR) antibodies only partially inhibited enzymic activities of XOR. The majority of both IgM and IgG anti-(human XOR) antibodies in serum occurred as immune complexes, suggesting that the specific antibodies have a protective role in removing potentially damaging XOR from the circulation.

Adult↗
PubMed1997

Induction of nitric oxide synthase in rat intestine by interleukin-1alpha may explain diarrhea associated with zinc deficiency.

Synthesis of inducible nitric oxide synthase (iNOS) in the intestine may result in local tissue damage. We investigated whether a challenge with interleukin-1alpha could give rise to intestinal iNOS expression and diarrhea in rats of differing zinc status. Weaning male rats were fed a zinc-deficient (ZD) diet (2 mg zinc/kg) for 4 wk to induce zinc deficiency or a zinc-supplemented diet [50.8 mg zinc/kg; controls, including pair-fed (PF ) and ad libitum (AL) consumption groups], and then subcutaneously injected with interleukin-1alpha (2 x 10(7) units/kg body wt). Without the interleukin-1alpha challenge, ZD rats had significantly lower plasma zinc concentration than the other groups. Intestinal metallothionein-1 mRNA abundance was lower in ZD rats than in AL rats. iNOS was expressed in the intestine of ZD rats but not in the others. None of the rats experienced diarrhea during the feeding period. Interleukin-1alpha led to a reduction in plasma zinc concentration, enhancement in intestinal metallothionein-1 mRNA levels, and expression of the intestinal iNOS gene in all groups. However, the abundance of iNOS mRNA was significantly higher in ZD rats than in the other groups. The presence of iNOS protein was demonstrated by immunohistochemical staining in the intestine of ZD rats that had been treated with interleukin-1alpha 12 h earlier. In addition, diarrhea occurred in most of the ZD rats and some of the PF rats but not in AL rats after interleukin-1alpha treatment. We conclude that ZD rats respond to interleukin-1alpha challenge more severely than controls, reflected by a more marked and prolonged iNOS expression and a greater incidence of diarrhea.

Animals↗
PubMed1996

The management of ectropion using the tarsoconjunctival composite graft.

OBJECTIVE: To demonstrate the technique, advantages, and results of autogenous tarsal grafts in the treatment of ectropion with lower eyelid retraction. DESIGN: Fourteen patients treated with autogenous tarsal grafts were evaluated. Follow-up ranged from 6 to 30 months (mean follow-up, 10 months). SETTING: All patients were treated at the University of Kansas Medical Center, Kansas City, December 1990 through June 1993. PATIENTS: Of 14 patients with ectropion who were treated with this technique, nine had facial nerve paralysis, three had had previous periorbital trauma resulting in cicatricial ectropion, one patient had orbital and congenital lower lid fibrosis, and one patient had Graves' ophthalmopathy with lower lid retraction. INTERVENTION: All patients underwent autogenous tarsal grafting. Eleven patients also underwent combined laterocanthal suspension (tarsal tongue technique). Seven patients underwent associated upper lid gold weight loading. One patient underwent a medial canthopexy. RESULTS: All patients had marked improvement functionally and cosmetically. One patient had slight under-correction. Results have remained stable for over 2 years. CONCLUSIONS: Autogenous tarsal grafts aid in the long-term stability of lower lid ectropion repair. Autogenous tarsal grafting has distinct advantages over other described techniques. When treating paralytic ectropion, other rehabilitative techniques must be additionally employed.

Adolescent↗
PubMed1996

Palmar bands in rheumatoid arthritis and other chronic conditions of the upper limb.

Palmar prolapse of the flexor tendons as a result of attenuation of the A1 and A2 pulleys occurs in rheumatoid arthritis and other conditions in which the joints of the fingers are chronically flexed. The flexor tendons may be palpable and sometimes visible as longitudinal bands crossing the palm. This can lead to confusion with the palmar bands of Dupuytren's disease. These bands are illustrated in a small series of patients and a serious complication of a misdiagnosis of Dupuytren's disease is presented. The pathogenesis of these palmar bands in rheumatoid arthritis is discussed.

Adult↗
PubMed1996

Dermal grafting for a patient with scleroderma. Case report.

Scleroderma is a connective tissue disorder which includes fibrosis of the skin. Facial skin contraction leads to loss of forehead, periorbital, and nasolabial wrinkling and at the same time causes radial furrows around the contracted oral opening (microstomia). The lips become retracted. We describe a 41 year old lady whose upper lip was treated by free dermal graft and injection of fat to improve her perioral aesthetic appearance. The skin was taken from the right submammary fold and the fat was obtained from the abdomen by liposuction. Excess fat was stored in a sterile container at -70 degrees C for future use. The patient made a satisfactory recovery and has asked for her lower lip to be treated in the same way.

Adipose Tissue↗
PubMed1995

Predictors of postnatal head molding in very low birth weight infants.

This study examined potential predictors of postnatal head molding in very low birth weight (VLBW) infants. Occipital-frontal circumference (OFC) and anterior-posterior (AP) and biparietal (BP) diameter measurements were obtained on 144 premature infants with birth weights of less than 1,500 gm. Measurements were obtained at four days of age (baseline) and weekly until discharge. Increasing gestational age, higher birth weight, and delivery by cesarean section predicted larger OFC at three weeks of life. Only baseline AP:BP measurements significantly predicted AP:BP measurements at week 3 and 5. Within-group t-tests indicated that the severity of head molding (as indicated by AP:BP ratio) increased throughout the first six weeks of life. Results indicate that postnatal head molding can be reliably predicted and that neonates with higher AP:BP ratios at birth are at greater risk for continued narrow, elongated head shape.

Cephalometry↗
PubMed1994

Precise repair of orbital maxillary zygomatic fractures.

OBJECTIVE: To demonstrate the techniques, advantages, indications, and potential pitfalls of the transconjunctival approach with lateral canthotomy, sublabial approach, and coronal approach in the treatment of complex trimalar fracture with associated blow-out fractures. DESIGN: All patients diagnosed as having complex trimalar fractures with or without blow-out treated by either of us over a 2-year period were included. Follow-up ranged from a minimum of 6 months to 2 years. SETTING: All patients were treated with December 1989 to December 1991 at either Louisiana State University Medical Center, Shreveport, or University of Kansas Medical Center, Kansas City. PATIENTS: Eighteen patients with complex trimalar fractures were included in this study. Eight patients had associated orbital blow-out fractures. Simple isolated arch fractures were excluded. INTERVENTION: All subjects underwent a transconjunctival approach with lateral canthotomy. Seven subjects also had associated sublabial flaps. Five patients required hemicoronal or coronal approaches. RESULTS: There were seven minor complications. Ninety-three percent (14/15 [three didn't respond to the survey]) of patients surveyed were either very satisfied or satisfied with their functional and cosmetic results. CONCLUSION: The management of complex trimalar fracture with blow-outs is greatly facilitated by the rational application of the described techniques.

Aged↗
PubMed1994

The biphasic mechanism of blood flow during cardiopulmonary resuscitation: a physiologic comparison of active compression-decompression and high-impulse manual external cardiac massage.

STUDY OBJECTIVE: Dismal survival in patients receiving standard manual CPR provided the rationale for the investigation of alternate methods of closed-chest circulatory support. Active compression-decompression (ACD) and high-impulse CPR are alternatives to standard manual CPR. This study was designed to test the hypothesis that ACD CPR provides superior cardiopulmonary hemodynamics due to an active decompression phase when compared with high-impulse manual CPR. PARTICIPANTS: Hemodynamics were studied during ACD and high-impulse CPR in eight adult beagles. DESIGN: Four animals were chronically instrumented and four were studied acutely. In an additional four animals, ACD was compared with sham ACD CPR. Each CPR technique was performed sequentially for 2 minutes, in random order, at a rate of 120, 50% duty cycle, and 1.5 to 2.0 in of compression depth. Measurements obtained included aortic, right atrial, left ventricular, and coronary perfusion pressures (in mm Hg); pulmonary artery flow, and left ventricular dimension. RESULTS: ACD maximized cardiopulmonary hemodynamics, including coronary perfusion pressure and stroke volume, compared with both high-impulse manual and sham ACD CPR. ACD CPR also increased left ventricular pressure change per unit time during decompression, and these changes correlated well with left ventricular volume changes. CONCLUSION: In the intact dog, ACD CPR generates physiologically and statistically superior hemodynamics when compared with high-impulse manual CPR. Improved blood flow seems to be related to more efficient ventricular filling and emptying. These findings emphasize the biphasic nature of CPR and the importance of active decompression.

Animals↗