Association of four HLA class III region genomic markers with HLA haplotypes

We have studied restriction fragment length polymorphism (RFLP) in the region 300 kb centromeric to the HLA-B locus. Four probes were used: one was genomic DNA derived from the tumor-necrosis factor (TNF)-beta gene, one was a cDNA for the BAT3 gene, and two single-copy genomic probes, R5A and M20A. The order of these markers from HLA-B towards the centromere is M20A, R5A, TNF and BAT3. The BAT3 and TNF-beta probes each detected two allelic bands with Taq I and Nco I digestion, respectively; the R5A and M20A probes each detected three polymorphic allelic bands with BstEII digestion. To determine if these restriction polymorphisms are preferentially associated with certain HLA-B and -DR haplotypes, a total of 153 HLA haplotypes was analyzed. The haplotypes A1, B8, DR3 and A3, B7, DR2 were each associated with a distinct combination of polymorphisms identified at these four sites, thereby demonstrating that the strong linkage disequilibrium characteristic of these haplotypes extends also to this segment of the class III region. In contrast, haplotypes that are not in positive linkage disequilibrium, such as A1,B8,DR4 and A2,B7,DR3, showed no preferential association with any of these polymorphisms. The antigens HLA-B27 and B35 were also found to be in positive linkage disequilibrium with RFLP patterns at three of these sites, and HLA-B14,B35,B44,Bw57 and Bw62 were found preferentially associated with polymorphisms at one or two of these sites, independent of the DR antigen present. These data further demonstrate that genetic linkage disequilibrium in the HLA class III region is complex and variable among different HLA haplotypes.

Delayed response to argon laser trabeculoplasty in monkeys. Morphological and morphometric analysis

In eight cynomolgus monkeys we performed argon laser trabeculoplasty and evaluated morphological changes in the trabecular meshwork (TM). Four weeks after laser treatment, the treated spots were detected as regions of flattened and collapsed beams covered by a cellular sheet extending from the corneal endothelium. The inner wall of Schlemm's canal beneath these regions was flat, with no vacuoles despite fixation with intraocular pressure maintained at 15 mm Hg. Adjacent nonlasered spots had wide open intertrabecular spaces with herniations of juxtacanalicular TM and of inner wall endothelium into and across the lumen of Schlemm's canal. The herniations contained chronic inflammatory cells and large vacuoles. Statistical morphometric analysis in three monkeys established that these herniations were significantly wider, more numerous, and contained more vacuoles than did control eyes. Our findings suggest that a biologic process is involved in these reactions to argon laser trabeculoplasty. Scarring is seen to obliterate TM in spots treated by the laser, and this apparently causes the flow of the aqueous humor to be diverted through adjacent nonlasered regions that become structurally altered to compensate for this overload of flow.

HLA polymorphisms in a Han Chinese population of Sichuan

This study reports the phenotype frequencies (PF) and gene frequencies (GF) of a homogeneous Sichuan Han Chinese population by typing of unrelated 229 individuals and 16 families for HLA-A, B, C, DR and DQ antigens. The frequencies of Bw67, Bw71, DRw12, DRw13 and DRw14 are the first to be reported in Chinese. Two two-locus haplotypes with significant linkage disequilibrium among the Sichuan have also been listed.

Short-term effect of argon laser trabeculoplasty in monkeys

We performed argon laser trabeculoplasty (ALT) in four cynomolgus monkeys and evaluated the morphologic changes in the trabecular meshwork one hour and 14 hours following the laser treatment. One hour after ALT, disruption of the trabecular beams and coagulative necrosis of the tissue were evident. Fragmented cells and fibrillar tissue debris were found in the trabecular spaces, accumulating in the juxtacanalicular region. This might explain the elevation of intraocular pressure seen immediately following ALT in some glaucomatous patients. Also, many trabecular endothelial cells were rounded up, displaying different stages of leaving the beams; these cells were actively phagocytic. Such stimulation of trabecular meshwork cells with subsequent removal of tissue debris might explain the temporary nature of elevation of intraocular pressure following ALT.

Q-switched neodymium-YAG laser trabeculopuncture in monkeys

In nine cynomolgus monkeys, trabeculopuncture was performed with a Q-switched neodymium-YAG laser, using a pulse energy of 5 to 7 millijoules and an exposure time of 14 nanoseconds. A penetration into Schlemm's canal was successfully achieved with two to four pulses; this penetration was accompanied by intraocular pressure (IOP) reduction and blood reflux into the anterior chamber. However, after eight days, IOP returned to baseline level, while white tissue was observed gonioscopically to fill in the puncture sites. Histologically, one hour after laser treatment, a blasting effect on the trabecular meshwork was observed with no signs of necrosis. Ater eight days, a hypertrophic scar formed, with the corneal endothelium extending over the scarred surface. At eight weeks and at six months after laser treatment, further shrinkage of the scar and the formation of a membrane over it was evident. Attempts to control scar formation by preventing blood reflux or injecting fluorouracil subconjunctivally for two weeks were unsuccessful. Scar formation at the trabecular puncture site severely limits the applicability of this potentially simple glaucoma treatment.