Lacunar Spaces Research Articles

Interobserver Reproducibility in the Diagnosis of Invasive Micropapillary Carcinoma of the Urinary Tract Among Urologic Pathologists

Invasive micropapillary carcinoma (IMPC) of the urinary tract is a well-described variant of the urothelial carcinoma with aggressive clinical behavior. Recent studies have proposed that patients with IMPC on transurethral resection should be treated with radical cystectomy regardless of the pathologic stage. Despite the potentially important therapeutic implications of this diagnosis, interobserver variation in the diagnosis of IMPC has not been studied. Sixty digital images, each from hematoxylin and eosin-stained slides, representing 30 invasive urothelial carcinomas (2 images per case), were distributed to 14 genitourinary subspecialists and each pathologist was requested to classify cases as IMPC or not. These cases included "classic" IMPC (n=10) and urothelial carcinoma with retraction and variably sized nests that might potentially be regarded as IMPC (n=20). The following 13 morphologic features were recorded as positive/negative for all cases independent of the reviewers' diagnoses: columnar cells, elongate nests or processes, extensive stromal retraction, lumen formation with internal epithelial tufting, epithelial ring forms, intracytoplasmic vacuolization, multiple nests within the same lacunar space, back-to-back lacunar spaces, epithelial nest anastomosis/confluence, marked nuclear pleomorphism, peripherally oriented nuclei, randomly distributed nuclei, and tumor nest size. In addition, a mean tumor nest size was calculated for each image based on the number of nuclei spanning the width of the nests. Interobserver reproducibility was assessed and the morphologic features were correlated with the classic IMPC and nonclassic/potential IMPC groups. In addition, the relationships between morphologic features, pathologists' interpretations, and case type (classic IMPC vs. nonclassic/potential IMPC) were evaluated using unsupervised hierarchical clustering analysis. Interobserver reproducibility for a diagnosis of IMPC in the 30 study cases was moderate (kappa: 0.54). Although classification as IMPC among the 10 "classic" IMPC cases was relatively uniform (93% agreement), the classification in the subset of 20 invasive urothelial carcinomas with extensive retraction and varying sized tumor nests was more variable. Multiple nests within the same lacunar space had the highest association with a diagnosis of classic IMPC. These findings suggest that more study of IMPC is needed to identify the individual pathologic features that might potentially correlate with an aggressive outcome and response to intravesical therapy.

Canaliculi in the tessellated skeleton of cartilaginous fishes

The endoskeletal elements of sharks and rays are comprised of an uncalcified, hyaline cartilage-like core overlain by a thin fibro-ceramic layer of mineralized hexagonal tiles (tesserae) adjoined by intertesseral fibers. The basic spatial relationships of the constituent tissues (unmineralized cartilage, mineralized cartilage, fibrous tissue) are well-known – endoskeletal tessellation is a long-recognized synapomorphy of elasmobranch fishes – but a high-resolution and three-dimensional (3D) understanding of their interactions has been hampered by difficulties in sample preparation and lack of technologies adequate for visualizing microstructure and microassociations. We used cryo-electron microscopy and synchrotron radiation tomography to investigate tessellated skeleton ultrastructure but without damage to the delicate relationships between constituent tissues or to the tesserae themselves. The combination of these techniques allowed visualization of never before appreciated internal structures, namely passages connecting the lacunar spaces within tesserae. These intratesseral ‘canaliculi’ link consecutive lacunar spaces into long lacunar strings, radiating outward from the center of tesserae. The continuity of extracellular matrix throughout the canalicular network may explain how chondrocytes in tesserae remain vital despite encasement in mineral. Extracellular fluid exchange may also permit transmission of nutrients, and mechanical and mineralization signals among chondrocytes, in a manner similar to the canalicular network in bone. These co-adapted mechanisms for the facilitated exchange of extracellular material suggest a level of parallelism in early chondrocyte and osteocyte evolution.

Osteocyte: the unrecognized side of bone tissue

Osteocytes represent 95% of all bone cells. These cells are old osteoblasts that occupy the lacunar space and are surrounded by the bone matrix. They possess cytoplasmic dendrites that form a canalicular network for communication between osteocytes and the bone surface. They express some biomarkers (osteopontin, beta3 integrin, CD44, dentin matrix protein 1, sclerostin, phosphate-regulating gene with homologies to endopeptidases on the X chromosome, matrix extracellular phosphoglycoprotein, or E11/gp38) and have a mechano-sensing role that is dependent upon the frequency, intensity, and duration of strain. The mechanical information transmitted into the cytoplasm also triggers a biological cascade, starting with NO and PGE(2) and followed by Wnt/beta catenin signaling. This information is transmitted to the bone surface through the canalicular network, particularly to the lining cells, and is able to trigger bone remodeling by directing the osteoblast activity and the osteoclastic resorption. Furthermore, the osteocyte death seems to play also an important role. The outcome of micro-cracks in the vicinity of osteocytes may interrupt the canalicular network and trigger cell apoptosis in the immediate surrounding environment. This apoptosis appears to transmit a message to the bone surface and activate remodeling. The osteocyte network also plays a recognized endocrine role, particularly concerning phosphate regulation and vitamin D metabolism. Both the suppression of estrogen following menopause and chronic use of systemic glucocorticoids induce osteocyte apoptosis. On the other hand, physical activity has a positive impact in the reduction of apoptosis. In addition, some osteocyte molecular elements like sclerostin, connexin 43, E11/gp38, and DKK1 are emerging as promising targets for the treatment of various osteo-articular pathologies.

Ultrastructure of the ovarian follicles in the placentotrophic Andean lizard of the genus Mabuya (Squamata: Scincidae)

We studied the ultrastructural organization of the ovarian follicles in a placentotrophic Andean lizard of the genus Mabuya. The oocyte of the primary follicle is surrounded by a single layer of follicle cells. During the previtellogenic stages, these cells become stratified and differentiated in three cell types: small, intermediate, and large globoid, non pyriform cells. Fluid-filled spaces arise among follicular cells in late previtellogenic follicles and provide evidence of cell lysis. In vitellogenic follicles, the follicular cells constitute a monolayered granulosa with large lacunar spaces; the content of their cytoplasm is released to the perivitelline space where the zona pellucida is formed. The oolemma of younger oocytes presents incipient short projections; as the oocyte grows, these projections become organized in a microvillar surface. During vitellogenesis, cannaliculi develop from the base of the microvilli and internalize materials by endocytosis. In the juxtanuclear ooplasm of early previtellogenic follicles, the Balbiani's vitelline body is found as an aggregate of organelles and lipid droplets; this complex of organelles disperses in the ooplasm during oocyte growth. In late previtellogenesis, membranous organelles are especially abundant in the peripheral ooplasm, whereas abundant vesicles and granular material occur in the medullar ooplasm. The ooplasm of vitellogenic follicles shows a peripheral band constituted by abundant membranous organelles and numerous vesicular bodies, some of them with a small lipoprotein core. No organized yolk platelets, like in lecithotrophic reptiles, were observed. Toward the medullary ooplasm, electron-lucent vesicles become larger in size containing remains of cytoplasmic material in dissolution. The results of this study demonstrate structural similarities between the follicles of this species and other Squamata; however, the ooplasm of the mature oocyte of Mabuya is morphologically similar to the ooplasm of mature oocytes of marsupials, suggesting an interesting evolutionary convergence related to the evolution of placentotrophy and of microlecithal eggs.

TNAP, TrAP, ecto‐purinergic signaling, and bone remodeling

Bone remodeling is a process of continuous resorption and formation/mineralization carried out by osteoclasts and osteoblasts, which, along with osteocytes, comprise the bone multicellular unit (BMU). A key component of the BMU is the bone remodeling compartment (BRC), isolated from the marrow by a canopy of osteoblast-like lining cells. Although much progress has been made regarding the cytokine-dependent and hormonal regulation of bone remodeling, less attention has been placed on the role of extracellular pH (pH(e)). Osteoclastic bone resorption occurs at acidic pH(e). Furthermore, osteoclasts can be regarded as epithelial-like cells, due to their polarized structure and ability to form a seal against bone, isolating the lacunar space. The major ecto-phosphatases of osteoclasts and osteoblasts, acid and alkaline phosphatases, both have ATPase activity with pH optima several units different from neutrality. Furthermore, osteoclasts and osteoblasts express plasma membrane purinergic P2 receptors that, upon activation by ATP, accelerate bone osteoclast resorption and impair osteoblast mineralization. We hypothesize that these ecto-phosphatases help regulate [ATP](e) and localized pH(e) at the sites of bone resorption and mineralization by pH-dependent ATP hydrolysis coupled with P2Y-dependent regulation of osteoclast and osteoblast function. Furthermore, osteoclast cellular HCO3(-), formed as a product of lacunar V-ATPase H(+) secretion, is secreted into the BRC, which could elevate BRC pH(e), in turn affecting osteoblast function. We will review the existing data addressing regulation of BRC pH(e), present a hypothesis regarding its regulation, and discuss the hypothesis in the context of the function of proteins that regulate pH(e).

Low-Frequency Sonophoresis: Ultrastructural Basis for Stratum Corneum Permeability Assessed Using Quantum Dots

Low-frequency sonophoresis (LFS) has been well documented to enhance the permeability of skin to macromolecular drugs via induction of localized transport regions. However, the organizational details of epidermis, specifically stratum corneum (SC), during sonophoresis are beyond the resolution limit of common histo-optical microscopy tools, which fail to reveal any notable structural alterations in these regions at a submicroscopic scale. Here we report, using quantum dots (QDs) as a tracer and confocal microscopy and transmission electron microscopy (TEM) (with OsO(4) and RuO(4) post-fixation) as visualization methods, on LFS-induced permeation pathways in the SC. QDs (20 nm diameter) penetrated well beyond the SC. TEM revealed that ultrasound significantly increased the frequency of occurrence of the otherwise scattered and separated lacunar spaces in the SC. A significant increase in lacunar dimensions was observed when 1% w/v sodium lauryl sulfate was added to the coupling medium. These studies show that LFS induces dilatation and higher connectivity of voids in the SC, possibly leading to formation of a three-dimensional porous network, which is capable of transporting QDs as well as macromolecules across the SC. This contention is consistent with previously conceived theoretical mechanistic understanding of LFS-induced enhanced transport across the skin.

Treating erectile dysfunction when PDE5 inhibitors fail

New oral drugs, especially phosphodiesterase type 5 (PDE5) inhibitors, have revolutionalised the treatment of erectile dysfunction by decreasing reliance on more invasive options. These inhibitors compete with cyclic GMP (guanosine...

Glucocorticoid-Treated Mice Have Localized Changes in Trabecular Bone Material Properties and Osteocyte Lacunar Size That Are Not Observed in Placebo-Treated or Estrogen-Deficient Mice

This study compares changes in bone microstructure in 6-month-old male GC-treated and female ovariectomized mice to their respective controls. In addition to a reduction in trabecular bone volume, GC treatment reduced bone mineral and elastic modulus of bone adjacent to osteocytes that was not observed in control mice nor estrogen-deficient mice. These microstructural changes in combination with the macrostructural changes could amplify the bone fragility in this metabolic bone disease. Patients with glucocorticoid (GC)-induced secondary osteoporosis tend to fracture at higher bone mineral densities than patients with postmenopausal osteoporosis. This suggests that GCs may alter bone material properties in addition to BMD and bone macrostructure. Changes in trabecular bone structure, elastic modulus, and mineral to matrix ratio of the fifth lumbar vertebrae was assessed in prednisolone-treated mice and placebo-treated controls for comparison with estrogen-deficient mice and sham-operated controls. Compression testing of the third lumbar vertebrae was performed to assess whole bone strength. Significant reductions in trabecular bone volume and whole bone strength occurred in both prednisolone-treated and estrogen-deficient mice compared with controls after 21 days (p < 0.05). The average elastic modulus over the entire surface of each trabecula was similar in all the experimental groups. However, localized changes within the trabeculae in areas surrounding the osteocyte lacunae were observed only in the prednisolone-treated mice. The size of the osteocyte lacunae was increased, reduced elastic modulus around the lacunae was observed, and a "halo" of hypomineralized bone surrounding the lacunae was observed. This was associated with reduced (nearly 40%) mineral to matrix ratio determined by Raman microspectroscopy. These localized changes in elastic modulus and bone mineral to matrix ratio were not observed in the other three experimental groups. Based on these results, it seems that GCs may have direct effects on osteocytes, resulting in a modification of their microenvironment. These changes, including an enlargement of their lacunar space and the generation of a surrounding sphere of hypomineralized bone, seem to produce highly localized changes in bone material properties that may influence fracture risk.

Modulation of Intrinsic Cavernous Tone and Nitric Oxide Production by Arginase in Rabbit Corpus Cavernosum

Arginase shares the common substrate L-arginine with nitric oxide synthase (NOS). We investigated the roles of NOS and arginase for modulating intrinsic and vasoconstrictor tone in rabbit corpus cavernosum (RCC). Isolated RCC tissues were used for isometric tension experiments, and NOS and arginase activities. The endothelium lining RCC lacunar spaces was disrupted and/or removed by saponin treatment. Following stretch of approximately 1gm NG-nitro-L-arginine methyl ester (L-NAME) as a NOS inhibitor caused endothelium dependent contraction, while the potent and specific arginase inhibitor N omega-hydroxy-nor-L-arginine (nor-NOHA) caused endothelium dependent relaxation. Relaxation with nor-NOHA was reversed by L-NAME. In the presence of 10 mM L-arginine 0.1 mM nor-NOHA was ineffective. Pretreatment with 0.1 mM L-NAME and 0.1 mM nor-NOHA did not significantly affect the vasoconstrictor response to phenylephrine. The magnitude of contraction with 0.1 mM L-NAME and relaxation with 0.1 mM nor-NOHA during contraction induced by phenylephrine were not significantly different from changes with L-NAME and nor-NOHA under intrinsic basal tone. In the enzymatic study NOS and arginase were detectable in cavernous homogenates. Nor-NOHA inhibited arginase but not NOS activity. Results indicate that basal nitric oxide production from the endothelium regulates intrinsic cavernous tone and endogenous arginase activity in the endothelium modulates tone by inhibiting nitric oxide production, presumably through competition with constitutive NOS for the common substrate L-arginine.

Ultrastructural Evidence of Stratum Corneum Permeabilization Induced by Photomechanical Waves

Photomechanical waves (high amplitude pressure transients generated by lasers) have been shown to permeabilize the stratum corneum in vivo and facilitate the transport of macromolecules into the viable epidermis. The permeabilization of the stratum corneum is transient and its barrier function recovers. Sites on the volar forearm of humans were exposed to photomechanical waves and biopsies were obtained immediately after the exposure and processed for electron microscopy. Electron microscopy showed an expansion of the lacunar spaces within the stratum corneum lipid bilayers but no changes in the organization of the secreted lamellar bodies at the stratum corneum-stratum granulosum boundary. The combination of photomechanical waves and sodium lauryl sulfate enhances the efficiency of transdermal delivery and delays the recovery of the barrier function of the stratum corneum. Electron microscopy from sites exposed to photomechanical waves and sodium lauryl sulfate showed that the lacunar spaces expanded significantly more and the secreted lamellar bodies also appeared to be altered. In either case, there were no changes in the papillary dermis. These observations support the hypothesis that the photomechanical waves induce the expansion of the lacunar spaces within the stratum corneum leading to the formation of transient channels.

Comparison between FLAIR Images and T2-weighted Fast Spin-echo Images of Cerebral Territory and Lacunar Infarction

Purpose: To assess the significance of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging in the diagnosis of intracranial infarctions and to find out differential points between central lacunar infarctions and perivascular spaces. Materials and Methods: We consecutively selected 25 cases of territorial infarction in 20 patients, 37 cases of central infarction in 40 patients, and 30 patients with perivascular space. Signal intensity and lesion conspicuity were analyzed and compared between FLAIR and FSE T2-weighted images, and differences in signal intensity between central infarction and perivascular spaces were determined. Results: Lesion conspicuity for FLAIR was better than for T2-weighted images in 12 and 15, worse in 4 and 24, and similar in 9 and 16 of territorial and central infarctions, respectively. In nine cases of territorial and one case of central infarction, there was associated hemorrhage. At FLAIR imaging, perivascular spaces showed a fine round low signal without a peripheral high signal rim in 17 patients but no demonstrable signals in 15. Differential diagnosis of perivascular spaces and central infarction was thus not difficult. Conclusion: FLAIR MRI was useful in the diagnosis of infarctions and in differentiating between central small lacular infarctions and perivascular spaces.

An improved staining method for intervertebral disc tissue

The objective of this study was to design a new staining procedure for human disc tissue for visualizing both collagen and proteoglycan-matrix components on the same histology section. Weigert's hematoxylin, alcian blue and picrosirius red were combined to produce distinctive staining of collagen (red), proteoglycans (blue) and cellular elements of the intervertebral disc. This novel stain reveals sharp details of collagen composition in the perilacunar, territorial and intraterritorial extracellular matrix, and concomitantly demonstrates the presence of proteoglycan accumulations around cells in the lacunar spaces and in the extracellular matrix. These details reveal variations within the tissue that would not be apparent with routine stains.

Plasma levels of cyclic guanosine-3',5'-monophosphate in the cavernous and systemic blood of healthy males during different functional conditions of the penis.

The relaxation of cavernous arterial and trabecular smooth muscle is dependent upon the stimulation of guanylyl cyclase activity by nitric oxide (NO), which is released from nerve terminals and endothelial cells within the cavernous tissue, and the subsequent accumulation of cyclic guanosine-3',5'-monophosphate (cGMP) in the intracellular space. The present study was undertaken to determine whether or not plasma levels of cGMP in the systemic and cavernous blood of healthy male subjects change from penile flaccidity to tumescence, rigidity and detumescence. Fifteen adult healthy males were exposed to visual and tactile erotic stimuli to elicit penile tumescence and rigidity. Whole blood was simultaneously aspirated from the corpus cavernosum and the cubital vein in the respective penile stages, and cGMP was determined in plasma aliquots by means of a radioimmunoassay. Mean systemic and cavernous plasma levels of cGMP in the blood samples obtained from the healthy volunteers ranged from 1.2-1.7 pmol/ ml. cGMP levels in the systemic circulation and in the cavernous blood did not change during developing erection, rigidity and detumescence. No significant differences were found between cGMP plasma levels in the systemic and cavernous blood in the different penile stages. Our results may reflect the fact that the stimulation of NO production in healthy males during sexual arousal and developing penile erection either does not yield substantial quantities of cGMP or that the rate of cGMP-extrusion from cavernous smooth muscle cells into the extracellular space accounts only for a minor fraction of plasma cGMP. Moreover, basal levels of cGMP in the blood flushing the lacunar spaces of the cavernous body in the state of developing erection may conceal any local release of cGMP that may occur within the penile erectile tissue. Thus, we conclude that the quantification of cGMP is of no use in the evaluation of the physiologic mechanisms of penile erection in vivo.

Evidence of a hypermineralised calcified fibrocartilage on the human femoral neck and lesser trochanter.

Femoral neck fractures are a major cause of morbidity and mortality in elderly humans. In addition to the age-related loss of cancellous bone, changes to the microstructure and morphology of the metaphyseal cortex may be a contributing factor in osteoporotic hip fractures. Recent investigations have identified a hypermineralised tissue on the neck of the femur and trochanteric region that increases in fractional area with advancing age in both males (Boyce & Bloebaum, 1993) and females (Vajda & Bloebaum, 1999). The aim of this study was to determine if the hypermineralised tissue previously observed on the proximal femur is calcified fibrocartilage. Regional variations in the fractional area of hypermineralised tissue, cortical bone, and porosity of the cortical bone along the neck of the femur and lesser trochanter were also quantified. Comparison of back scattered electron and light microscope images of the same area show that regions of hypermineralised tissue correlate with the regions of calcified fibrocartilage from tendon and capsular insertions. The hypermineralised tissue and calcified fibrocartilage had similar morphological features such as the interdigitations of the calcified fibrocartilage into the bone, lacunar spaces, and distinctly shaped pores adjacent to the 2 tissues. Regions of the neck that did not contain insertions were covered with periosteum. There were no regional differences (P > 0.05) on the superior and inferior femoral neck in terms of the percentage area of hypermineralised calcified fibrocartilage, cortical bone, or cortical bone porosity. The lesser trochanter exhibited regional differences in the fractional area of hypermineralised calcified fibrocartilage (P = 0.007) and cortical bone (P = 0.007) but not porosity of the cortical bone (P > 0.05). The effects of calcified fibrocartilage on femoral neck periosteal expansion, repair, and mechanics are unknown, but may play a role in osteoporotic fractures and intracapsular fracture healing.

Schneckenbecken dysplasia, radiology, and histology

To our knowledge this is the first report of Schneckenbecken dysplasia with the development of hydrops early in the second trimester. The radiological findings showed the typical hypoplastic iliac bones with medial extension and very flattened, on lateral view, oval-shaped vertebral bodies and short long bones. The histology showed hypercellular and hypervascular cartilage with chondrocytes with centrally located nucleus. The absence of the lacunar space as described before was also observed in some chondrocytes in our case. This male fetus was the product of consanguineous parents of Mediterranean origin compatible with autosomal recessive inheritance.

Determination of nitric oxide metabolites by means of the Griess assay and gas chromatography-mass spectrometry in the cavernous and systemic blood of healthy males and patients with erectile dysfunction during different functional conditions of the penis.

Recent research implicated that the relaxation of cavernous arterial and trabecular smooth muscle-- the crucial event in penile erection--is initiated by the release of nitric oxide (NO) from nerve terminals within the cavernous tissue as well as from the endothelia that line the lacunar spaces and the intima of penile arteries. The present study was undertaken to determine whether plasma levels of the NO metabolites nitrate (NO3-) and nitrite (NO2-) in the systemic and cavernous blood of male subjects change during different penile conditions, and whether there is a difference in the NO3- and NO2- levels of normal males and patients with erectile dysfunction (ED). Twenty-four potent adult male volunteers and 15 patients with ED were exposed to visual and tactile erotic stimuli in order to elicit penile tumescence and, in the group of healthy volunteers, rigidity. Whole blood was aspirated from the corpus cavernosum and the cubital vein, and NO3- and NO2- levels were determined in plasma aliquots by means of the Griess reaction and a method combining gas chromatography and mass spectrometry (GC-MS). The mean systemic and cavernous plasma NO3-/NO2- level in blood samples obtained from the healthy volunteers was 25-31 microM when determined by means of the Griess reaction and 37-41 microM when measured by GC-MS. Both approaches revealed that NO3-/NO2- levels in the peripheral and cavernous blood do not change appreciably during developing erection, rigidity and detumescence. Moreover, no significant differences were found between NO3-/ NO2- plasma levels in the systemic and cavernous blood samples taken from the normal subjects and patients during penile flaccidity, tumescence and detumescence. Our results may reflect the fact that NO metabolism in the corpora cavernosa in the phases of penile tumescence and rigidity may account for only a minor fraction of local levels of NO3- and NO2-, which may also derive from exogenous sources. Moreover, the basal levels of NO metabolites in the blood flushing the lacunar spaces of the cavernous body in the state of developing erection could conceal any release of NO that may occur within the penile tissue. Thus, we conclude that the quantification of NO metabolites by means of advanced detection methods, such as GC-MS, is of no use in the workup of ED.

Relationships between methane production and emission to lacunal methane concentrations in rice

We measured lacunal methane concentrations in field‐grown rice plants as a correlative to both methane production and emissions. Using a gas‐tight syringe, 100‐μL samples were withdrawn from plant lacunar spaces below the water level and diluted to provide enough volume for analysis by gas chromatography. Lacunal methane concentrations increased throughout the season and, for each sampling date, were usually significantly higher in the cultivars Mars and Cypress (high emitters) when compared with Lemont and Della (low emitters). The field site influenced lacunal methane concentrations, wherein greater lacunal methane concentrations corresponded with greater methane. Methane emission rates were positively correlated with plant lacunal methane concentrations for each cultivar, with an improvement in the relationship during the preheading season. With increases in methane production determined by emissions following field‐induced anoxia, lacunal methane concentrations increased accordingly. Lacunal methane concentrations also clearly increased as plant biomass increased, but the relationship depended on field location, which also influenced emissions. Sampling lacunal methane concentrations of rice plants, although labor intensive, is quite flexible, using little field equipment, and may provide an effective alternative to large‐scale flux measurements in areas not easily accessible.

Peliosis hepatis with initial presentation as acute hepatic failure and intraperitoneal hemorrhage in children

Peliosis hepatis, a condition characterized by the presence of blood-filled lacunar spaces in the liver, usually has a chronic presentation pattern and is mainly reported in adult patients in association with chronic wasting disorders and after administration of various drugs. The present report concerns two previously healthy young children in whom peliosis hepatis initially presented as acute hepatic failure and who had Escherichia coli pyelonephritis. Both patients had active intraperitoneal hemorrhage from the peliotic liver lesions, and liver ultrasonography showed multiple hypoechoic areas of different sizes, which in this context should suggest the diagnosis. One child died from hypovolemic shock and the other recovered. This study indicates that acute peliosis hepatis can be a serious life-threatening disease in children.

Clinical Pharmacology of α1-Adrenoceptor Antagonists

Benign prostatic hyperplasia (BPH) is the most prevalent condition to affect men beyong middle age. α₁-adrenoceptor blockers have been used in the treatment of BPH for more than 20 years and their effect on the lower urinary tract is now well established. These agents as a class have produced consistent improvements in both symptom scores and urinary flow rates in around 60–70% of patients treated. This efficacy is balanced against a small, but significant, incidence of side-effects, that consist of headaches, dizziness, nasal stuffiness, tiredness and very occasionally postural hypotension. There are important other effects of α₁-adrenoceptor blockers; for example in men with hypertension, these agents generally produce a clinically significant reduction in both systolic and diastolic blood pressures. There is also well documented evidence of a reduction in LDL cholesterol levels as well as serum triglycerides. A new and interesting observation is that patients receiving certain α₁-adrenoceptor blockers notice improvement in their sexual function and in particular in the quality of their erectile response. This effect has been attributed to decreased sympathetic vasoconstrictor tone to the helicine arteries supplying the lacunar spaces of the corpora cavernosa in the penis. In summary α₁-adrenoceptor blockers produce significant improvements in symptoms and flow rates in patients with bladder outflow obstruction due to benign prostatic hyperplasia. This is balanced against a small but significant incidence of side-effects, but some of these side-effects, such as a reduction in blood pressure in hypertensive patients, improvement in lipid profile and improvement in erectile function could be construed as beneficial.

LOCALIZATION OF P 2Y1 PURINOCEPTOR TRANSCRIPTS IN THE RAT PENIS AND URINARY BLADDER

Purpose The aim of this study was to determine the expression and localization of the P2Y 1 purinoceptor mRNA in rat penis and urinary bladder using reverse transcription polymerase chain reaction (RT-PCR), northern blotting and in situ hybridization (ISH). Materials and Methods RT-PCR: First strand cDNA was prepared from rat penis and urinary bladder dome total RNA and used for PCR with primers designed to amplify fragments of the P2Y 1 purinoceptor cDNA sequence. Northern blotting: PCR products were subcloned into the pGEM-5Zf(+) plasmid vector, sequenced and random primer labeled using 32 P. Labeled probe was hybridized. ISH: Digoxigenin labeled cRNA probes were synthesized by in vitro transcription. Results P2Y 1 purinoceptor mRNA was detected by RT-PCR analysis in both rat penis and urinary bladder. RNA blotting using a P2Y 1 purinoceptor cDNA probe revealed a single transcript of 4.2kb in both tissues. This band was the same size as that expressed by the heart, which contains high levels of P2Y 1 purinoceptor (Burnstock, G.: Physiological and pathological roles of purines: an update. Drug. Dev. Res., 28: 195, 1993). By ISH, P2Y 1 purinoceptor mRNA was localized in detrusor smooth muscle cells and blood vessels in urinary bladder. In penis, positive signals were detected in endothelial cells which line the lacunar space and blood vessels. No hybridization was seen in corpus cavernosum smooth muscle cells and urethra. Conclusion These results indicate that mRNAs for P2Y 1 purinoceptor are expressed in detrusor smooth muscle cells and blood vessels of rat urinary bladder. However, in penis, this receptor is expressed in endothelial cells which lines the lacunar space and blood vessels, but not expressed in corpus cavernosum smooth muscle cells and urethra.