Hyaluronic acid in the normal and glaucomatous optic nerve

Eighteen normal human eye-bank eyes (age: 18-81 years), five fetal eyes (16-24 weeks), 11 primary open-angle glaucoma (POAG) eyes (age: 76-89 years), and two Schnabel's cavernous optic atrophy eyes were examined using a biotinylated-hyaluronan binding protein to study the changes in the distribution of hyaluronic acid (HA) in the fetal, adult and glaucomatous optic nerve head. The vitreous body served as a positive control. Sections treated with Streptomyces hyaluronidase were used to confirm specificity. Monoclonal antibodies to myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) were used as additional controls. In fetal optic nerve, HA was localized in blood vessels, peripapillary sclera and the pial septae in the retrolaminar nerve. No staining was associated with axons. Staining for MBP was negative. In adults, HA was found surrounding the myelin sheaths in the retrolaminar nerve; staining decreased with age. In contrast, HA staining in myelinated peripheral nerves (e.g. ciliaries) remained unchanged with age. HA also was localized to the adventitia of arteries and veins throughout the posterior segment. Compared to age-matched normal eyes, HA staining was virtually absent around myelin sheaths of the retrolaminar nerve in POAG eyes. Similar changes were not found in other HA positive structures. In Schnabel's cavernous optic atrophy. HA was present in increased amount in the atrophic area, but virtually absent in the remaining retrolaminar nerve. HA staining was invariably positive in vitreous, and Streptomyces hyaluronidase treated sections were negative. In adults, staining of MBP was associated with the myelin sheath in the retrolaminar nerve. In contrast to HA, staining of MBP was unchanged with age and in POAG. In Schnabel's atrophy, MBP staining disappeared only in the atrophic area. HA in the retrolaminar optic nerve appears to be associate with the space-filling matrix between myelin sheaths. HA is not present in the axon bundles prior to myelination of the optic nerve. HA in the retrolaminar optic nerve appears to decrease with age and is further reduced in POAG; however, corresponding changes are not found in MBP or in peripheral nerves. Perhaps, decreased amounts of HA is related to a higher susceptibility to elevated intraocular pressure or to optic nerve atrophy. In Schnabel's cavernous optic atrophy, HA is present in increased amount only in the atrophic area while MBP is markedly decreased, suggesting in situ production of HA in areas of optic nerve atrophy.

Percutaneous transluminal coronary angioplasty for acute myocardial infarction: initial experience in 43 cases

OBJECTIVE

To evaluate the initial experience with the use of percutaneous transluminal coronary angioplasty (PTCA) in the set of acute myocardial infarction (AMI).

METHODS

Between October 1993 and April 1996, PTCA was performed in 43 patients (34 male, 9 female) with initial onset of AMI. These patients ranged in age from 40 to 74 years (mean +/- SD, 60.3 3 +/- 9.2). Primary PTCA was performed in 16, rescue PTCA in 8, and semi-elective PTCA in 19 patients.

RESULTS

The initial success was achieved in 95.3% (41/ 43). Failed angioplasty occurred in 2 patients, with acute reocclusion after rescue PTCA (this patient died of cerebral stroke 3 days later) in one patient, and small local intimal dissection during semi-elective PTCA in another patient.

CONCLUSION

PTCA was a safe and effective approach in the treatment of AMI in the present study patients, with a high primary success and low acute complication rate.

Perforin, a cytotoxic molecule which mediates cell necrosis, is not required for the early control of mycobacterial infection in mice

Host defense against mycobacterial infection requires the participation of monocytes and T cells. Both CD4+ and CD8+ T cells have been shown to be important in resistance to mycobacterial infection in vivo. The main contribution of CD4+ T cells to the protective antituberculosis response involves the production of Th1-type cytokines, including interleukin-2 (IL-2) and gamma interferon (IFN-gamma). CD8+ T cells have been considered to be responsible primarily for cytotoxicity mediated by toxic molecules, including perforin. CD8+ T cells may also elaborate Th1-type cytokines, such as IFN-gamma, in response to the infection. To elucidate the contribution of perforin-mediated target cell death to the control of mycobacterial infection in vivo, mice with a disruption in the perforin gene (P-/-) were infected with Mycobacterium bovis BCG or M. tuberculosis Erdman for 5 and 13 weeks, respectively. At 1, 3, 5, and 13 weeks postinfection, the number of viable mycobacteria in the lungs, spleens, and livers of mice were determined by CFU assay. The infected tissues were examined histologically, and cytokine mRNA levels in the spleens of these mice were determined. Similar studies were carried out in Fas receptor-defective (CBA/lpr(cg)) mice to evaluate the contribution of this alternative cytotoxic pathway to the control of mycobacterial infection. The absence of either perforin gene function or Fas receptor gene function did not modify the course of experimental mycobacterial infection in these mice. In addition, both P-/- and Fas receptor-defective mice appeared to have a compensatory activation of cytokine genes, even in the absence of the experimental infection. P-/- mice had a mean 3.4- to 5-fold increase in mRNA levels for IL-10, IL-12p35, IL-6, and IFN-gamma. Similarly, Fas receptor-defective mice had a mean 3- to 3.6-fold increase in mRNA levels for IFN-gamma, IL-12p35, and IL-10. Our results indicate that both perforin-mediated cytotoxicity and Fas-mediated cytotoxicity do not appear to be necessary for the early control of mycobacterial infection in vivo.

The involvement of interleukin (IL)-15 in regulating the differentiation of granulated metrial gland cells in mouse pregnant uterus

Previous studies have suggested that granulated metrial gland (GMG) cells are bone marrow-derived lymphoid cells, which differentiate in situ in the mouse pregnant uterus into natural killer (NK)-like cells. Similar to NK cells, GMG cells express an abundant level of cytolytic mediators such as perforin. The factor(s) regulating the differentiation of GMG cells remain(s) to be identified, although cytokines previously implicated in the stimulation/activation of NK cells (e.g., IL-2, IL-6, IL-7, and IL-12) can be considered as potential candidates. Recently, IL-15, a novel cytokine, which displays biological activities similar to IL-2, has also been shown to be capable of activating NK cells. Using reverse transcription-polymerase chain reaction (RT-PCR) analysis, we have demonstrated in the present study that IL-15 and its cognate receptor, but not the other cytokines, are expressed in the mouse pregnant uterus, with a time course concomitant with those of cytolytic mediators in differentiated GMG cells. Moreover, IL-15, though not IL-2, is capable of inducing the expression of perforin and granzymes in pregnant uterine tissues explanted in vitro. Data obtained from in situ hybridization study have suggested that the macrophages present in the pregnant uterus may be responsible for the production of IL-15. These results suggest that IL-15 is involved in regulating the differentiation of GMG cells during mouse pregnancy.

Interleukin-15 induces the expression of mRNAs of cytolytic mediators and augments cytotoxic activities in primary murine lymphocytes

Interleukin-15 (IL-15) is a novel cytokine displaying biological activities that overlap those of interleukin-2 (IL-2). Like IL-2, IL-15 has been shown to be capable of stimulating the proliferation of human natural killer cells and PHA-treated T lymphocytes and of generating cytotoxic activity in stimulated lymphocyte populations. Using primary murine lymphocytes as a model in the present study, we have investigated the effects of IL-15 on the induction of the expression of mRNAs encoding different lymphocyte cytolytic mediators and the enhancement of cytolytic activities. Using reverse transcription-polymerase chain reaction analysis, both IL-15 and IL-2 have been shown to induce the expression of mRNAs for perforin, granzymes A and B, interferon-gamma, and Fas ligand in primary murine splenic lymphocytes. The induction effect of IL-15 has been shown to be at least partially independent of cell proliferation. Although IL-15 and IL-2 appear to be comparably effective in inducing the expression of cytolytic mediator mRNAs, the former is less potent in eliciting functional cytolytic activity in stimulated lymphocyte populations. The inadequate cytolytic activity of IL-15-stimulated lymphocytes may in part be due to the less efficient production of cytolytic mediator proteins, e.g., perforin and granzyme A, in these cells.

[Reversal of adriamycin or vincristine resistance by tetrandrine in human cancer cells in vitro]

In an in vitro culture system of human cancer cells MCF-7 and its adriamycin-resistant line MCF-7/Ad or KB and its vincristine-resistant line KBv200, tetrandrine was found to exhibit significantly selective anticancer activity against the drug-resistant cancer cell MCF-7/Ad. In addition, essentially complete reversal effects of tetrandrine on drug resistance were observed in MCF/Ad or KBv200.

[Effect of the T4 on the viscera and embryo of perinatal mice]

58 Female Kun Ming mice of perinatal stage (from the 15th day of pregnacy to the 21th day after birth) were fed with Tripcholorolide (T4) isolated from multiglycosides of Tripterygium wilfordii (GTW) at a doze of 0.6 mg/kg for group 1 or 0.3 mg/kg for group 2 per day for 4 weeks. Lactation was decreased in some females and some F1 off spring died. The succinic dehydrogenase (SDH) activity of the mice liver were increased due to the destruction of its mitocondian. Liver cells degenerated and glycogen decreased. Distal tubules of kidney degenerated. Heart and spleen were normal. T4 was also fed to 10 female mice from the 5th to 17th day of pregnacy. However, neither the absorbed fetus nor dead fetus increased.

An STS-based map of the human genome

A physical map has been constructed of the human genome containing 15,086 sequence-tagged sites (STSs), with an average spacing of 199 kilobases. The project involved assembly of a radiation hybrid map of the human genome containing 6193 loci and incorporated a genetic linkage map of the human genome containing 5264 loci. This information was combined with the results of STS-content screening of 10,850 loci against a yeast artificial chromosome library to produce an integrated map, anchored by the radiation hybrid and genetic maps. The map provides radiation hybrid coverage of 99 percent and physical coverage of 94 percent of the human genome. The map also represents an early step in an international project to generate a transcript map of the human genome, with more than 3235 expressed sequences localized. The STSs in the map provide a scaffold for initiating large-scale sequencing of the human genome.

[Protection from procarbazine induced testicular toxicity by gonadal steroid hormones]

To confirm the claims that the procarbazines (PCZ) effect on stem spermatogonia can be overcome by gonadal steroid hormones,mature,LBNF1 male rats were implanted with silastic capsules containing testosterone (T 200 mm) + estradiol (E 50 mm). The silastic capsules of control and TE groups were removed 24 hours after the PCZ injection and the rats were sacrificed 9 weeks later. The functional status of the testis and the hormonal parameters at the time of the injection of PCZ were measured and correlated with the degree of protection ,as measured by the recovery of sperm counts. The results indicated that testosterone and estradiol does protect spermatogenesis from PCZ intoxification. To determine whether the protection is specific for stem spermatogonia, we also measured body weight loss 3-4 days, lymphocyte counts 1 day, and spermatocyte count 9 days after PCZ treatment. There were no differences in the dose response curves of these three assays between the hormone and sham treated rats. The lack of protection indicates that the hormonal protection of stem spermatogonia was not due to the alterations in either systemic or testicular pharmacokinetics of spermatocyte. We conclude that A3 spermatogonia and preleptotene spermatocyte are sensitive to PCZ and there is no evidence of hormonal protection for the differentiated spermatogonia and preleptotene spermatocyte.

[Effect of Astragalus membranaceus on T-lymphocyte subsets in patients with viral myocarditis]

The efficacy of Astragalus membranaceus (AM) oral liquor combined with routine therapy and routine therapy alone on T-lymphocyte subsets of peripheral blood in viral myocarditis patients have been studied. The results showed that the T-lymphocyte subsets profile and OKT4/OKT8 ratio of peripheral blood were significantly lower in viral myocarditis patients than that in healthy control (P < 0.05, 0.01). Routine therapy combined with AM could significantly enhance OKT3, OKT4 and OKT4/OKT8 ratio in the above-mentioned patients (P < 0.05, 0.01). The possible pharmacodynamic mechanism of improved cell immunity in viral myocarditis patients by combining routine therapy with AM was discussed.

Bacterially expressed F1-20/AP-3 assembles clathrin into cages with a narrow size distribution: implications for the regulation of quantal size during neurotransmission

F1-20/AP-3 is a synapse-specific phosphoprotein. In this study we characterize the ability of bacterially expressed F1-20/AP-3 to bind and assemble clathrin cages. We find that both of two bacterially expressed alternatively spliced isoforms of F1-20/AP-3 can bind and assemble clathrin as efficiently as preparations of F1-20/AP-3 from bovine brain. This establishes that the clathrin assembly activity found in F1-20/AP-3 preparations from brain extracts is indeed encoded by the cloned gene for F1-20/AP-3. It also demonstrates that post-translation modification is not required for activation of the clathrin binding or assembly function of F1-20/AP-3. Ultrastructural analyses of the clathrin cages assembled by bacterially expressed F1-20/AP-3 reveals a strikingly narrow size distribution. This may be important for the regulation of quantal size during neurotransmission. We also express the 33 kD NH2-terminus of F1-20/AP-3 in E. coli, and measure its ability to bind to clathrin triskelia, to bind to clathrin cages, and to assemble clathrin triskelia into clathrin cages. It has been suggested that the 33 kD NH2-terminus of F1-20/AP-3 constitutes a clathrin binding domain. We find that the bacterially expressed 33 kD NH2-terminus of F1-20/AP-3 binds to clathrin triskelia, fails to bind to preassembled clathrin cages, and is not sufficient for clathrin assembly. The finding that the 33 kD NH2-terminus of F1-20/AP-3 binds to clathrin triskelia but fails to assemble clathrin triskelia into clathrin cages is consistent with the published proteolysis studies. The finding that the 33 kD NH2-terminus of F1-20/AP-3 fails to bind to clathrin cages is novel and potentially important. It is clear from these experiments that the 33 kD NH2-terminus of F1-20/AP-3 is sufficient to carry out some aspects of clathrin binding; however it appears that defining the regions of the protein involved in clathrin binding and assembly may be more complex than originally anticipated.

Inhibition of clathrin assembly by high affinity binding of specific inositol polyphosphates to the synapse-specific clathrin assembly protein AP-3

Bacterially expressed synapse-specific clathrin assembly protein, AP-3 (F1-20/AP180/NP185/pp155), bound with high affinity both inositol hexakisphosphate (InsP6) (Kd = 239 nM) and diphosphoinositol pentakisphosphate (PP-InsP5) (Kd = 22 nM). The specificity of this ligand binding was demonstrated by competitive displacement of bound [3H]InsP6. IC50 values were as follows: PP-InsP5 = 50 nM, InsP6 = 240 nM, inositol-1,2,4,5,6-pentakisphosphate (Ins(1,2,4,5,6)P5) = 2.2 microM, inositol-1,3,4,5,6-pentakisphosphate (Ins(1,3,4,5,6)P5) = 5 microM, inositol-1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) > 10 microM, inositol-1,4,5-trisphosphate (Ins(1,4,5)P3) > 10 microM. Moreover, 10 microM inositol hexasulfate (InsS6) displaced only 15% of [3H]InsP6. The physiological significance of this binding is the ligand-specific inhibition of clathrin assembly (PP-InsP5 > InsP6 > Ins(1,2,4,5,6)P5); Ins(1,3,4,5,6)P5 and InsS6 did not inhibit clathrin assembly. We also observed high affinity binding of InsP6 to purified bovine brain AP-3. We separately expressed the 33-kDa amino terminus and the 58-kDa carboxyl terminus, and it was the former that contained the high affinity inositol polyphosphate binding site. These studies suggest that specific inositol polyphosphates may play a role in the regulation of synaptic function by interacting with the synapse-specific clathrin assembly protein AP-3.

Antispermatogenic effect of Tripterygium wilfordii and tripchlorolide (T4) on rat gametogenesis and spermatozoa

The multiglycosides of Tripterygium wilfordii (TII), a ready-made Chinese herbal medicine used for the treatment of rheumatoid arthritis, have been shown to cause oligospermia in patients. In the present study, the antifertility effects of TII and tripchlorolide (T4, isolated from TII) were observed in male rats. In rats fed with TII at a dose of 10 mg.kg.d for 7 weeks, the seminiferous tubules were essentially not influenced. However, most of the sperm heads along the surface of the tubular lumen were transformed from the normal sickle-shaped to round shaped, suggesting a possible mutagenic action. There was minimal testicular change but prominent epididymal spermatozoa damage in all rats treated with T4 (0.05 mg.kg.d) for 7 weeks. The epididymal spermatozoa showed various structural abnormalities, including disrupted connecting pieces and cracked midpieces, and more than 80% of the spermatozoa were decapitated. No significant changes were seen in the main visceral organs. The data suggest that T4 may have good prospects as a male contraceptive.

Effect of intra-vas deferens injection of gossypol-polylactic acid on fertility and spermatogenesis in rats

In order to reduce gossypol's side effects, we applied a controlled drug release system. In this system gossypol is carried on a polymer of polylactic acid which controls drug release and can also be injected into the vas deferens so that the drug can act continuously and directly on spermatogenesis. We used a single dose of gossypol-polylactic acid (0.35 mg/0.1 ml for each vas deferens) which is only 0.2% of the usual antifertility dose. Fertility tests showed that male rats became infertile 4 weeks after intravasal injection of gossypol-polylactic acid. Gross and microscopic findings in the heart, liver, kidneys and lungs revealed no evidence of pathologic change. Treated rats gained body weight as fast as did the controls. The majority of spermatozoa showed breakage of the axial fibers, indicating that gossypol had diffused into the testes. The fertility of the treated rats recovered four to eight months after treatment. Gossypol-polylactic acid injected into the vas deferens exhibited a low degree of toxic side effects and a high antifertility activity, and is therefore an important approach to decreasing the side effects while enhancing the antifertility specificity of gossypol.

The actions of capsaicin applied topically to the skin of the rat on C-fibre afferents, antidromic vasodilatation and substance P levels

1. Single applications of solutions of capsaicin were made to the intact skin of anaesthetized rats and the effects on cutaneous blood flow and the firing of C-nociceptor afferents determined. Blood flow was measured by laser-Doppler flowmetry. C-fibre activity was recorded from filaments dissected from the saphenous nerve. 2. Following the application of a capsaicin solution (concentration > or = 1 mM) to rat saphenous skin, low frequency firing occurred in C-polymodal nociceptors that sometimes continued for > 10 min. At the some time, large increases in skin blood flow occurred exceeding 300% in some instances. 3. After the initial excitation, some C-polymodal nociceptors lost their sensitivity to pressure whilst their sensitivity to heat was lost or enhanced depending on the vehicle used. 4. Sensitivity of C-polymodal nociceptors to heat recovered in < 1 day following a single application of 33 mM capsaicin. Thresholds to mechanical pressure, however, were still significantly elevated by 123% on day 1, but had recovered on day 2. 5. Vasodilatation in response to saphenous nerve stimulation ('antidromic vasodilatation') was significantly reduced by 35%, 2 days after a single application of 33 mM capsaicin, but was normal at 4 days. 6. Following a single application of 33 mM capsaicin, skin substance P levels fell to only half the normal value at day 1 and remained at this level throughout the 4 day period examined. 7. It is suggested that the ability of relatively low concentrations of capsaicin to desensitize C-fibre nociceptors may underlie the analgesic action of topical capsaicin in man.

[Pathogenetic and clinical significance of peripheral activated T-lymphocyte subsets in Basedow's disease]

The peripheral activated T-cell subsets which express concurrently DR and CD antigens were determined in 22 patients with Graves' disease using the fluorescence-rosette double labelling technique. In the active phase of the disease a decrease in the percentage of CD8+ cells, an increase in the CD4+/CD8+ ratio and an elevation of various DR+CD+T-lymphocytes was found. A concurrent marked increase in DR+CD4+ cells accounts for an abnormality in the equilibrium of activated T-lymphocyte subsets and an increase in DR+CD4+/DR+CD8+ ratios. In comparison with the active phase the DR+CD3+ and DR+CD4+ cells decreased in remission, but DR+CD8+ cells remained unchanged. The decrease in the ratio of CD4+/CD8+ cells was less marked than that of the DR+CD4+/DR+CD8+ cells, which fell into the normal range. Our results suggest an excessive activation of T-helper cells as well as a deficiency in T-suppressor cells which may play an important role in the pathogenesis of Graves' disease.

[Antispermatogenic effects of multiglycosides of Tripterygium wilfordii and monomer T4 in the testes and epididymal spermatozoa of rats]

The antispermatogenic effects of the multiglycosides of Tripterygium wilfordii (GTW) and monomer T4 isolated from GTW on the testes and epididymal spermatozoa of rats were examined microscopically following silver staining. The dosages of GTW and T4 were 10mg/kg.d and 0.05 mg/kg.d, respectively, fed for 7 weeks via gastric intubation. Different degrees of damage to the testis and epididymal tubes were found in rats treated with GTW. Deformed, round-headed sperms and exfoliated cells (mainly spermatids and occasionally pachytene spermatocytes) were seen in the tubular lumen of the epididymis. Spermatids with deformed acrosomal vesicles were also commonly observed. No significant pathological changes were seen in other internal organs. T4 mainly caused damage to the spermatozoa in the epididymis. Under the dosage of 0.05mg/kg.d the sperm count was almost nil, but no discernible changes in the seminiferous tubules, epididymal epithelia, Leydig cells or Sertoli cells were found. The antifertility potency of T4 was 200 times stronger than that of GTW.

[A study on components and compound prescription of huangqin decoction]

The results obtained from the pharmacological experiments have preliminarily demonstrated that the compound prescription is better than its individual component drug in the range and potency of pharmacological activities. In the prescription Radix Scutellariae plays a principal role in pharmacological effects. Radix Scutellariae and Radix Paeoniae Alba can potentiate each other. Radix Glycyrrhizae and Fructus Jujubae in the compound prescription also exhibit biological activities to some extent. The relieving effect of the prescription for spasm and pain may result from the synergistic interaction between Radix Paeoniae Alba and Radix Glycyrrhiza, and the heat clearing and diarrhea stopping action is due to the biological activity of Radix Scutellariae.

[Treatment and prevention of asymmetrical intrauterine growth retardation with huoxue huayu prescription]

The purpose of this study was to observe the therapeutical and preventive effect of the compound prescriptions of Huoxue Huayu (promoting blood circulation to remove stasis, PBCRS) and Yiqi Huoxue, replenishing Qi to remove stasis, RQRS) on experimental intrauterine growth retardation (IUGR) caused by passive smoking during pregnancy in rats. The fetal average birth weight and the erythrocyte deformability were found to be significantly reduced in the smoke-exposed group compared with the control group. However, there was a significant increase of blood viscosity (at both shear rates), Hb, Ht, MCV, MCH levels and the erythrocyte fragility in the smoke-exposed group in comparison with the control group. After the mother-rats were given PBCRS and RQRS prescriptions during gestation, the fetal average birth weight and erythrocyte deformability were markedly increased. The blood viscosity, Hb, Ht, MCV, MCH levels and erythrocyte fragility of pregnant rats were decreased. No differences were found in the control group and the two treated groups. The electronic microscope observation of erythrocyte shape shows there were some protrusions on the surface of red cells in the smoke-exposed group. The protrusions were significantly reduced in the two treated groups, which was similar to the control group. The erythrocyte deformability, the blood viscosity, Hb, Ht, MCV, MCH levels indicate that there was a significant correlation between them and the fetal average birth weight respectively. This study indicates that blood stasis is one of the pathogenetic mechanisms of asymmetrical IUGR and that the PBCRS recipe could improve intrauterine growth environment of fetal which could treat and prevent IUGR in obstetrics.

[A preliminary study on the pharmacology of the compound prescription huangqin tang and its component drugs]

Results obtained from the pharmacological experiments demonstrated that the compound prescription Huangqin Tang and its component drugs, roots of Paeonia lactiflora, Scutellaria baicalensis and Glycyrrhiza uralensis, and the fruit of Ziziphus jujuba showed marked anti-inflammatory effect. The compound prescription and its component drugs, except the peony root, possessed significant antispastic effect. Antipyretic effect of Radix Scutellariae, Radix Glycyrrhizae and Huangqin Tang was suggested. Huangqin Tang, Radix Paeoniae alba, and Radix Glycyrrhizae showed marked analgesic effect. In addition, the experiments confirmed that both Huangqin Tang and single Radix Scutellariae have sedative effect.

Multipoint linkage of 9 anonymous probes to HPRT, factor 9, and fragile X

We have analyzed the segregation of restriction fragment length polymorphisms (RFLPs) associated with 9 anonymous probes detecting loci DXS10, DXS15, DXS19, DXS37, DXS51, DXS52, DXS98, DXS99, and DXS100 and probes for HPRT and F9 in a set of 40 families segregating fragile X (fra(X]. Using two-point and multipoint analysis, we have established their relative genetic locations. The results indicate that DXS99 and DXS10, unlike previous reports, are not tightly linked to F9. A new locus was found to map within the F9 - fra(X) region. DXS98 showed 6% recombination with fra(X) and appeared to be the closest locus to fra(X). These results will be useful for mapping the relative position of newly defined X probes in this region and for future genetic studies of families with fra(X), hemophilia B, or Lesch-Nyhan mutations.