Sex determining gene on the X chromosome short arm: dosage sensitive sex reversal

The present review article summarizes current knowledge concerning the sex determining gene on Xp21, termed DSS (dosage sensitive sex reversal). The presence of DSS has been based on the finding that, in the presence of SRY, partial active Xp duplications encompassing the middle part of Xp result in sex reversal, whereas those of the distal or proximal part of Xp permit male sex development. Because Klinefelter patients develop as males, it is believed that DSS is normally subject to X-inactivation, and that two active copies of DSS override the function of SRY, resulting in gonadal dysgenesis because of meiotic pairing failure. It may be possible that DSS encodes a target sequence for repressing function of SRY or that DSS is involved in an X chromosome-counting mechanism. Molecular approaches have localized DSS to a 160 kb region and isolated candidate genes such as DAX-1 and MAGE-Xp, but there has been no formal evidence equating the candidate gene with DSS. In addition to its clinical importance, the exploration of DSS must provide a useful clue to phylogenetic studies of sex chromosomes and dosage compensation.

Ultra-high-resolution scanning electron microscopy of the continuity of cytoplasmic and luminal membranes in frog oxyntic cells

BACKGROUND

Despite numerous previous studies, the presumed continuity of the luminal and tubulovesicular membranes in frog oxyntic (oxyntico-peptic) cells remains to be convincingly demonstrated. This study was undertaken to clarify this question by ultra-high-resolution scanning electron microscopy of specially prepared frog stomach specimens before and during histamine stimulation.

METHODS

Fasted Japanese meadow frogs stimulated with histamine were used. Oxyntic cell cytoplasmic matrix was removed by the aldehyde-osmium-DMSO-osmium maceration procedure and impregnated with osmium-hydrazine. Specimens were examined without metal coating.

RESULTS

In the resting oxyntic cell, the luminal membrane had closely packed surface folds forming a rather flat surface with a few short microvilli. In the cytoplasm, flattened 200-500 nm vesicles were interconnected by numerous slender 20-60 nm tubules forming the tubulovesicular network. Occasional slender tubular branches were found in continuity with the luminal membrane. After histamine stimulation, the number and length of microvilli and surface folds increased, whereas the tubulovesicular membrane system decreased. Sites of clear continuity between the luminal and tubulovesicular membranes were not abundant but were clearly demonstrated in histamine-stimulated oxyntic cells. The small size of the tubules connecting the tubulovesicular system to the plasma membrane renders this observation by transmission electron microscopy very difficult. In these specimens, the clear continuity of the tubulovesicular network to the luminal plasma membrane became more evident.

CONCLUSIONS

This study confirms previous findings of increased luminal membrane and depletion of the tubulovesicle system. The demonstration of continuity between these two compartments in our SEM preparations supports the hypothesis of direct transfer of tubulovesicular membrane to oxyntic cell luminal secretory membrane.

Short- and long-term effects of nisoldipine on cardiac function and exercise tolerance in patients with hypertrophic cardiomyopathy

Nisoldipine is a second generation dihydropyridine calcium antagonist having characteristics of strong coronary artery dilating effect and less negative inotropic action. The purpose of this study was to evaluate the effect of nisoldipine on the cardiac function (systolic and diastolic) and the exercise tolerance, in patients with hypertrophic cardiomyopathy (HCM).

SUBJECTS

Twenty-three patients with HCM were studied.

METHODS

We measured the following indices using M-mode and pulsed wave Doppler echocardiography before and after nisoldipine therapy; left ventricular fractional shortening (LVFS), isometric relaxation time (IRT), deceleration half-time (DHT) of early diastolic mitral (E) flow, late diastolic mitral (A) flow and A/E ratio. Symptom-limited treadmill exercise test was performed. Exercise tolerance (EX) time was measured. Nisoldipine of 10 mg/day was orally administered. Same tests were repeated on day 14 and after 6 months.

RESULTS

1) Short-term effects; LVFS did not change (55.9 +/- 5.9%-->57.0 +/- 7.4%, NS) after 2 weeks. However, LV diastolic function significantly improved (IRT; 92.1 +/- 7.7 ms-->85.2 +/- 11.6 ms, p < 0.05, DHT; 70.7 +/- 16.2 ms-->63.3 +/- 3.7 ms, p < 0.05). EX time increased (8.9 +/- 2.6 min-->10.0 +/- 3.3 min, p < 0.05), 2) Long-term effects; LV diastolic function had a tendency toward improvement, but is statistically not significant (IRT; 91.1 +/- 7.6-->83.8 +/- 11.6 ms, DHT; 73.1 +/- 23.4-->61.0 +/- 11.4 ms, A/E; 1.26 +/- 0.29-->1.11 +/- 0.36) after 6 months. EX time was significantly increased (9.4 +/- 1.7--> 10.1 +/- 1.7 min, p < 0.05).

CONCLUSIONS

Nisoldipine improved LV diastolic dysfunction and exercise tolerance in patients with HCM. These effects were similar to the first generation calcium antagonists. LV diastolic dysfunction may be improved due to the reduction of intracellular calcium concentration and the relief of myocardial ischemia by strong coronary artery dilating effect. However, nisoldipine did not affect the LV systolic function because of its less negative inotropic effect.

Mechanism of multiple aminoglycoside resistance of kasugamycin-producing Streptomyces kasugaensis MB273: involvement of two types of acetyltransferases in resistance to astromicin group antibiotics

The biochemical basis for the multiple resistance to aminoglycoside antibiotics (AGs) of kasugamycin-producing Streptomyces kasugaensis MB273 was studied. The strain was resistant to a wide range of deoxystreptamine (DOS)-containing AGs as well as astromicin (ASTM) group antibiotics. These AGs strongly inhibited in vitro polyU-directed polyphenylalanine-synthesis using ribosomes from the strain, while they were acetylated and inactivated by the MB273 cell free extract supplemented with acetyl-CoA. It seemed thus likely that the acetyltransferase activity played a critical role for the multiple AG resistance. The acetylation was selective to AGs with 2'-NH2, suggesting the involvement of aminoglycoside 2'-N-acetyltransferase, AAC (2'). Interestingly, the acetylation of istamycin B (ISM-B; an ASTM group AG) resulted in the formation of two different products (1-N-acetyl ISM-B and 2"-N-acetyl ISM-B) at a similar ratio. In this context, an AAC (2') gene cloned as an ISM-B resistance gene from the strain MB273 directed the conversion of ISM-B to only 1-N-acetyl ISM-B. It seemed likely that two types of AACs [AAC(2') and a novel one] were involved in the mechanism of resistance to ASTM group AGs.

A panel of radiation hybrids defining the 7q31-q32 region of human chromosome 7

Mouse A9 cells containing human chromosome 7 tagged with pSV2neo were irradiated with X-rays and fused to A9 cells to isolate G418-resistant clones. From these clones, we selected radiation hybrids that contained 10-40 Mb of human DNA apparently at a single site of their genome by FISH analysis using human repetitive sequences as a probe. Then we made a panel of hybrids that contained various fragments of the 7q31-q32 region and cover its entire region altogether by PCR with STS markers of human chromosome 7. This panel is useful in chromosome transfer experiments since the dominant selective marker neo gene is attached to human DNA.

Potentiated cAMP rise in metabotropically stimulated rat cultured astrocytes by a Ca2+-related A1/A2 adenosine receptor cooperation

Adenosine agonists favoured an intracellular Ca2+ rise in cultured type 1 astrocytes if the metabotropic glutamate receptors were concomitantly stimulated by (2S, 1's, 2's)-2-(carboxycyclopropyl)glycine (L-CCG-I; group II agonist), quisqualate (group I agonist) or 1-aminocyclopentane-trans-1, 3-dicarboxylic acid (t-ACPD; groupI/II agonist). Since the generation of a Ca2+ signal reflected a newly adopted adenosine A1 receptor action, we tested the possible consequence that the established opposing control of the cellular cAMP content by inhibitory A1 and stimulatory A2 receptor activation was also altered. During metabotropic receptor stimulation by LCCG-I, quisqualate or t-ACPD, the non-selective adenosine agonist 2-chloroadenosine (Cl-adenosine) caused a potentiated cAMP increase which markedly exceeded that produced by Cl-adenosine alone. This cAMP potentiation resulted from altered and Ca2+-dependent A1/A2 receptor cooperation. It was abolished by A1 receptor blockade and could not be achieved in the presence of t-ACPD by the A1 agonist R(-)N6-(2-phenylisopropyl)-adenosine or by the A2 agonist 5'-N-ethyl carboxyamidoadenosine alone, but obtained using their combination. The cAMP potentiation was blocked by intracellular Ca2+ chelation and the required A1 receptor action could be mimicked by a Ca2+ signal generated by the P2y receptor agonist adenosine 5'-(beta-thio)diphosphate. The results support the conclusion that nanomolar concentrations of adenosine may influence astrocyte reactions by stimulating Ca2+ and cAMP-dependent signalling cascade.

Comparison of mucosal microvasculature between the proximal and distal human colon

The microcirculation of the human colon with special reference to the differences in microvascular architecture between the proximal and distal colon was studied by scanning electron microscopy with vascular corrosion casting technique. The subsurface capillary networks of the ascending colon were honeycomb-like and multi-layered, with an average number of capillary layers per capillary loop of 3.28 +/- 1.10 (mean +/- SD). Whereas, those of the sigmoid colon were almost single-layered, and the average number of capillary layers was 1.19 +/- 0.39. In the cross-section of vascular casts of both parts of the colon, the ascending capillaries originating from the submucosal arterioles ascended into the mucosal layer and joined into the subsurface capillary networks, which drained into the collecting venules near the surface. The mean diameter of the collecting venules of the ascending and the sigmoid colon was 29.3 +/- 6.41 microns and 19.48 +/- 2.23 microns, respectively. From these findings, it is speculated that the multi-layered capillary networks of the proximal colon are closely related to the greater water absorption and electrolyte transport activities compared to those of the distal colon.

Coarctation of the aorta and renal hypoplasia in a boy with Turner/Noonan surface anomalies and a 46,XY karyotype: a clinical model for the possible impairment of a putative lymphogenic gene(s) for Turner somatic stigmata

This paper describes a 12-year-old Japanese boy with coarctation of the aorta, renal hypoplasia, Turner/Noonan surface anomalies, and a 46,XY karyotype. Although the patient might represent an exceptional case of Noonan syndrome, the combination of the somatic stigmata appears to be consistent with a mutation of the putative lymphogenic gene(s) for Turner somatic stigmata.

[A histopathological study of corneal amyloidosis secondary to trichiasis]

We present a case of secondary corneal amyloidosis whose etiological mechanism was investigated by immunohistochemistry and electron microscopy. A 48-year-old woman had suffered from trichiasis in the right eye for 35 years, and developed secondary corneal amyloidosis, a phenomenon previously described but whose etiological mechanism has not been explained. Slitlamp examination of the cornea revealed a white excrescence with a diameter of 2 mm. The lesion was excised and examined by light and electron microscopy. Large deposits of an amorphous eosinophilic material were observed beneath the atrophic epithelium. Amyloid was detected in these deposits using Congo red stain, polarized light, and electron microscopy. Neither vascularization nor infiltration of inflammatory cells was observed. Immunohistochemical tests for protein AL, protein AA, prealbumin, beta 2-microglobulin and cytokeratin in paraffin sections were all negative. Characteristic findings were observed in the border zone between the basal cells and the deposits. Numerous digitiform cell processes and membrane-bound globular fragments of basal cells were seen in the superficial region of the deposits. The cell membrane of some globules was interrupted and the contents appeared to have been discharged into the stroma. These findings suggest that basal cells of the corneal epithelium provide an amyloid precursor on the stroma.

Modulation of glial cell signaling by adenosine and pharmacological reinforcement. A neuroprotective strategy?

In view of the increasing evidence that a pathological glial activation plays a significant role in the development of neurodegenerative diseases, we investigated the underlying molecular signaling as a possible target for the pharmacological therapy. Here, we are particularly focusing on the endogenous modulation of the CA2+ and cyclic nucleotide-dependent signaling by the nucleoside adenosine and its reinforcement by the xanthine derivative propentofylline (PPF). As an experimental model, we used cultured rat microglial cells and astrocytes that are immature, show a high proliferation rate, and resemble in several aspects pathologically activated glial cells. A prolonged increase of the cellular cAMP level favored the differentiation of cultured astrocytes and associated properties required for the physiological nerve cell function. On the other hand a strengthening of the cyclic nucleotide-dependent signaling inhibited potentially neurotoxic properties of cultured microglial cells. Similar effects were obtained by treatment with propentofylline, which mimicked modulatory adenosine effects and increased the intracellular level of cAMP and cGMP. Such a pharmacological glial cell conditioning, obtained by modifying the strength and the timing of these second messengers, may provide a therapy of neurodegenerative diseases in which a pathological activation of microglial cells and astrocytes is discussed to playa pathogenic role.

Enzymatic 2'-N-acetylation of arbekacin and antibiotic activity of its product

Aminoglycoside antibiotics (AGs) with a free 2'-amino group were subjected to enzymatic N-acetylation using a cell free extract that contained an aminoglycoside 2'-N-acetyltransferase, AAC (2'), derived from a kasugamycin-producing strain of Streptomyces kasugaensis. TLC and antibiotic assay of the incubated reaction mixtures revealed that a modified compound retaining substantial antibiotic activity was formed from arbekacin (ABK), while modification of the other AGs resulted in the marked decrease in antibiotic activity. Structure determination following isolation from a large scale reaction mixture showed the modified ABK to be 2'-N-acetyl ABK. In addition, 2',6'-di-N-acetyl ABK was formed as a minor product. The same conversion also occurred with dibekacin (DKB) resulting in the formation of 2'-N-acetyl DKB and 2',6'-di-N-acetyl DKB. MIC determination showed antibacterial activity (1.56 approximately 3.13 micrograms/ml) of 2'-N-acetyl ABK against a variety of organisms. By contrast, 2'-N-acetyl DKB showed no substantial antibiotic activity. We believe 2'-N-acetyl ABK has the highest and broadest antibacterial activity, compared with known N-acetylated AGs.

Ischemic neuronal damage. How does mild hypothermia modulate it?

The significance of mild hypothermia as a therapeutic measure for ischemic brain damage is presented on the basis of different experimental results. An extracellular glutamate surge, a sustained activation of N-methyl-D-aspartate (NMDA) receptors, and an enhancement of DNA binding activity to transcription factor AP-1, all being key items directly linked to excitotoxic neuronal damage, are deeply affected by slightly lowering temperature (mild hypothermia [MH]). The cellular mechanism of MH seems rather nonspecific but tends to collectively involve these key items rendering neurons resistant to ischemic damage. Clinical application of MH should be a great challenge to relieve deadly effects on central neurons.

Role of aspartate in ischemic spinal cord damage

To study the potentially different roles of the excitatory amino acids glutamate and aspartate in the development of ischemic injury of the spinal cord, we measured their release from cultured neurons and glial cells under ischemic conditions. We also examined changes in intracellular Ca2+ concentration and the damage elicited in cultured neurons by glutamate and aspartate. Hypoxic-hypoglycemic treatment (in vitro ischemia) elicited a rapid release of the excitatory amino acids from cultured spinal cord neurons and glial cells, but the release was greater from glial cells than from neurons. The ischemia-induced glutamate release from glial cells was transient; the aspartate release lasted longer, although the peak level was smaller than that of glutamate. In cultured neurons, a remarkable elevation in intracellular Ca2+ concentration was induced by glutamate but not by a lower concentration (10 microM) of aspartate, which is below the neurotoxic dose. At the higher concentration (100 microM), both excitatory amino acids induced a marked elevation in intracellular Ca2+ concentration and neuronal death. These results indicate that aspartate is less potent than glutamate in eliciting excitatory neurotransmission under normal physiological conditions. However, under pathological conditions such as ischemia, the increased release of aspartate from glial cells may add to the damage to neighboring neurons.

Electron microscopic study of the morphological changes of gastric mucous cell induced by Helicobacter pylori in human gastric ulcers

Specimens from 8 cases of human gastric ulcers infected with H. pylori, 3 cases of gastric ulcers without H. pylori infection and mucosal specimens infected with H. pylori from 3 cases of early gastric cancers obtained at surgery were studied by transmission electron microscopy. In the surrounding epithelium of the ulcer, when present, the bacteria were preferentially located at the luminal side of the apical junctional complexes. This was accompanied by dome-like bulging of the apical cytoplasm, but the epithelial continuity was maintained. A consistent finding was the apocrine-like release of the apical cytoplasm into the lumen. In addition, there were cells with marked apical protrusions and cells with dissolution of mucous granules. Degenerative changes, such as cellular edema, vacuole formation and disruption of cell membrane were also observed. The cells which had shed their apical mucous area appeared to degenerate causing massive cell exfoliation and formation of denuded lamina propria. Similar changes of the surface mucous cells were observed in the mucosal specimens infected with H. pylori obtained from early gastric cancers, but such cell pathology was scarce in samples of the gastric ulcers without H. pylori infection. In some ulcers infected with H. pylori, the bacteria were also observed on the surface of the regenerating epithelial cells at the ulcer base. These findings suggest that H. pylori infection is an important factor in the development of gastric ulcers and in the prevention or delay in ulcer healing.

Three-dimensional organization of lymphatics in the dog stomach: a scanning electron microscopic study of corrosion casts

The three-dimensional organization of the lymphatics in the dog stomach was studied by scanning electron microscopy of corrosion casts, which were made by direct parenchymal injection of low-viscosity Mercox-resin into the mucosa and the muscular layers. Although the organization of lymphatics in the stomach has been studied by a variety of methods, the origin of the lymphatics and their connection in each layer has not been clearly defined. In this study, using dog stomach because of its structural similarity to the human stomach, we defined the lymphatic structure in all gastric layers, with lymphatics absent in the upper two-thirds of the lamina propria mucosae. They were first encountered at the deepest level of the lamina propria, immediately above the lamina muscularis mucosae. These lymphatics were composed of single-layered irregular meshes. Slender lymphatics arising from this network passed through the lamina muscular is mucosae and drained into the lymphatic plexus, which was composed of thicker lymphatics at the uppermost layer of the submucosa. Lymphatic valves were frequently seen in this plexus. From this plexus, slender connecting lymphatics with valves extended straight downward without lateral communications and drained into the lymphatic plexus at the deepest layer of the submucosa. This latter plexus, composed of large-caliber lymphatics, issued flattened lymphatics which formed a three-dimensional network in the muscular layer. The subserosal lymphatics were composed of thick lymphatics with tortuous courses and drained into the efferent lymphatics.

Assessment and comparison of algorithms for in vivo ESR-CT imaging of bioradicals with L-band microwaves

In ESR-CT imaging, it is much more difficult to obtain satisfactory images than in imaging with other modalities, since two inverse problems, i.e. deconvolution of observed data and reconstruction from projections, must be solved. In this work, suitable algorithms for ESR-CT are examined using simulations and experiments. The algorithms were applied to actual data from a rat's head and a satisfactory reconstructed image was obtained from the viewpoint of morphological imaging. Several properties of the algorithms are discussed: (1) which combination of deconvolution and reconstruction method is favorable, (2) whether or not a raw differential signal should be integrated before deconvolution and reconstruction procedures, and (3) how SIRT, which offers good performance in ESR-CT, depends on an initial value and a noise type.

A spatiotemporal study on the distribution of intraperitoneally injected nitroxide radical in the rat head using an in vivo ESR imaging system

We have developed a rapid-scan in vivo electron spin resonance (ESR) imaging system operating at 700 MHz based on an air-cored two-coil Helmholtz designed resistive magnet. Using this system, we performed ESR-CT for the intraperitoneally injected nitroxide radical, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl, in the rat head. The imaging data were collected over the time course range from 5 to 47 min after injection at an interval of 3 min and a series of ESR-CT images were reconstructed at the same slice plane (1 cm anterior to interaural line). The series of ESR-CT images thus obtained by rapid scans provided detailed spatiotemporal information on the distribution of the injected nitroxide radical in the rat head. The brain was imaged as a nitroxide-deficient area while the blood vessels and/or extracranium tissues as a nitroxide-rich area. During periods when high intensities of ESR signals were maintained, spots of nitroxide-accumulation were imaged at the central part of the brain. The spots were assigned to the middle sized blood vessels in the brain.

Expression of the human cGMP-dependent protein kinase II gene is lost upon introduction of SV40 T antigen or immortalization in human cells

We have cloned a human cGMP-dependent protein kinase type II cDNA to examine its gene expression in terms of cellular senescence and/or immortalization. The genetic locus was mapped to band 4q21 by FISH. Northern blot analysis revealed that expression of the type II gene was markedly decreased or lost in mortal or immortal human fibroblasts producing SV40 T antigen. Also in various immortalized cell lines tested, the gene was not expressed. In normal diploid fibroblasts, the gene was constitutively expressed during cell-cycle and population doubling levels (PDLs).

A morphological study on the histogenesis of human colorectal hyperplastic polyps

BACKGROUND & AIMS

Little is known about the histogenesis of human colorectal hyperplastic polyp, although this polyp is clinically very common. Therefore, the structural features of the polyp and their implications regarding histogenesis were studied.

METHODS

A total of 261 foci were examined using scanning electronmicroscopic observation of the isolated crypt and surface structure, NaOH cell maceration and scanning electron microscopy, dissecting microscopy, and standard histological analysis.

RESULTS

In surface view, each polyp crypt was discretely demarcated as in the normal crypt, suggesting that the crypt epithelium had not replaced the adjoining crypt. Notches at the base and various stages of branching, observed in 21.8% of the isolated crypts, were considered to reflect crypt fission. Several polyps with a single crypt mouth consisting of fissioned multiple crypts suggested polyp origin from a single crypt and growth by fission. Juxtaposition of small polyps and their fusion suggested polycentric origin. Almost all polyps showed increased stromal inflammatory cell infiltration and/or a lymphoid follicle at the base.

CONCLUSIONS

Hyperplastic polyps originate by the apparent fusion of single abnormal crypts within a small region of mucosa. The polyps grow by fission of the crypt and fusion of the polycentrically originated polyps. Chronic inflammation has some relation to this process.

Orally administered bovine lactoferrin inhibits bacterial translocation in mice fed bovine milk

Feeding of bovine milk to mice induced a high incidence of bacterial translocation from the intestines to the mesenteric lymph nodes, and the bacteria involved were mainly members of the family Enterobacteriaceae. Supplementation of the milk diet with bovine lactoferrin or a pepsin-generated hydrolysate of bovine lactoferrin resulted in significant suppression of bacterial translocation. Our findings suggest that this ability of lactoferrin to inhibit bacterial translocation may be due to its suppression of bacterial overgrowth in the guts of milk-fed mice.

A novel spin probe with long life in vivo for ESR imaging

A dextran-bonded nitroxide radical (TEMPO-DX) was synthesized to obtain a radical with long life in vivo for ESR imaging. TEMPO-DX was injected intravenously into a rat tail vein and the decrease in ESR intensity in the collected, circulating blood was followed. The result showed that the half life of TEMPO-DX in vivo was 30 min, the longest value reported so far and more than 30 times longer than the corresponding radicals of the six-membered piperidine ring, which means that the bonding of a radical to the polymer greatly prolonged life. The stabilities of TEMPO-DX against the reduction with L-ascorbic acid and the rat liver homogenate were also examined and compared with those of the 3-carbamoyl-2,2,5,5-tetramethylpyrolidin-1-yloxy (CPROXYL) known as a radical stable in vivo. TEMPO-DX was shown not to be as stable as CPROXYL, thus in vivo stability of TEMPO-DX arises from the fact that it is slowly absorbed into the tissues where the radicals are quenched. An ESR image of the mouse head domain was obtained only by an intravenous injection of TEMPO-DX solution into the tail vein.

Free radical imaging by electron spin resonance computed tomography in rat brain

Images of nitroxide radicals were obtained from the brains of living rats following intracarotid injection of imaging agent, [2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinylox y] (16 DS) using L-band electron spin resonance computed tomography (ESR-CT). The image patterns obtained from the 3-carbamoyl-2,2,5,5-tetramethyl-1-pyrrolinyloxy injected rats showed the agent in tissues of the cranium but not within the brain. The uptake of 16 DS was found in the cortex, hippocampus, striatum, midbrain, pons medulla oblongata and cerebellum, and nuclei, mitochondria, synaptosomes of the cerebrum after intracarotid injection of 16 DS using an x-band ESR spectrometer. These results suggest that 16 DS penetrates the blood brain barrier.

Short stature in a girl with partial monosomy of the pseudoautosomal region distal to DXYS15: further evidence for the assignment of the critical region for a pseudoautosomal growth gene(s)

This report describes a 12 year 10 month old girl with short stature and a non-mosaic 46,X,Xp+ karyotype. Her height remained below −2 SD of the mean, and her predicted adult height (143 cm) was below her target height (155·5 cm) and target range (147·5 cm−163·5 cm). Cytogenetic and molecular studies showed that the Xp+ chromosome was formed by an inverted duplication of the Xp21.3−Xp22.33 segment and was missing about 700 kb of DNA from the pseudoautosomal region distal to DXYS15. The results provide further support for the previously proposed hypothesis that the region between DXYS20 and DXYS15 is the critical region for a pseudoautosomal growth gene(s).