Unifocal Peritoneal Malignant Mesothelioma as Initial Presentation of Lynch Syndrome: A Case Report and Brief Review

Introduction/Objective

Peritoneal malignant mesothelioma (pMM) has scarcely been reported in the context of Lynch Syndrome (LS). No cases have directly led to a diagnosis of LS. We report an unusual case of pMM presenting as a localized mass, leading to the diagnosis of LS.

Methods/Case Report

A 55 year old female with no prior oncologic history presented with a solitary epigastric mass. Her mother and maternal relatives had colonic, gastric and ovarian cancers. Imaging studies revealed a perigastric mass abutting the left liver. The resected 9.8 cm mass showed a variegated histology with tubulopapillary formations and solid sheets. The neoplastic cells also showed variable cytologic features including anisocytosis, pleomorphic nuclei, multinucleation, prominent nucleoli, intranuclear pseudoinclusions, and rhabdoid features. A dense intratumoral and peritumoral lymphoplasmacytic infiltrate was present. Epithelioid pMM was confirmed with expression of cytokeratin 5/6, calretinin, WT-1, and thrombomodulin and loss of MOC31. Abnormal loss of MSH2 and MSH6 was seen (retained expression MLH1/PMS2 expression), suggesting high-level microsatellite instability. A germline pathogenic variant of MSH2 was identified.

Results (if a Case Study enter NA)

NA.

Conclusion

We report the first case of LS presenting as an atypical (unifocal) pMM showing variegated histology and lymphocytic infiltrate. Microsatellite instability in pMM is rare and has only been reported in known LS patients. Awareness of the pMM within LS is evolving and atypical features may prompt evaluation of DNA microsatellite repair system, with implications for the patient (treatment/screening) and their family.

Transitioning a cardiovascular health and rehabilitation programme to a virtual platform during covid 19

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

Our Hearts Our Minds

Purpose

Can a virtual cardiovascular prevention and rehabilitation programme be as effective as face-to-face programme.

Background

The Our Hearts Our Minds (OHOM) prevention and rehabilitation programme rapidly transitioned to a virtual platform in the covid era.  Here we compare if a virtual programme potentially could offer the same standard of the nursing intervention (education, smoking cessation, medical risk factor management and psychosocial health) as the previous face to face programme

Methods

Both the initial assessment (IA) and end of programme (EOP) assessments were conducted via telephone/video as per patient preference. The following measures were recorded at both time points (home blood pressure (BP) monitors were provided)

Smoking (self report) BP/Heart rate, Lipids/HbA1c (facilitated by phlebotomy hub), cardio protective drugs (doses, adherence), Hospital Anxiety and Depression score, EuroQoL

Nursing Intervention Smoking cessation counselling and pharmacotherapy where appropriate

Weekly meeting with cardiologist to optimise BP and lipid management and up titration cardio protective drugs

Bimonthly virtual coaching consultation for monitoring/goal resetting

Bimonthly group video education sessions

Results

From April to November 2020, of the 432 referrals received 400 were eligible with 377 accepting the offer of an IA (94% response rate). 262 have had an IA with the remaining 115 awaiting an assessment date.  Of the completed IA’s 257 were willing to attend the programme (98% uptake).  120 had been offered an end of programme assessment with 114 attending (96% of those offered). The results for the virtual programme were then compared to the same period one year previously when the programme was fully face to face and are outlined in the table below.

The comparison of results delivered via remote delivery are remarkably similar to those achieved in the previous year delivered via face to face.

Conclusion

Initial data has shown that virtual delivery of the nursing component of the OHOM prevention/rehabilitation programme was highly acceptable to patients and was as effective as that of the traditional face to face service.

Table 1 below exhibits the clinical and patient-reported outcomes.

Selective central vascular ligation (D3 lymphadenectomy) in patients undergoing minimally invasive complete mesocolic excision for colon cancer: optimizing the risk-benefit equation

AIM

Complete mesocolic excision (CME) with central vascular ligation (CVL) has been advocated for right colon adenocarcinoma (RC), but the radicality of vascular dissection remains controversial. Our aim is to report outcomes of selective CVL (D3 lymphadenectomy) during minimally invasive CME for RC.

METHOD

A prospective database identified patients who were treated for RC between 2009 and 2016. Minimally invasive CME was standard. The radicality of lymphadenectomy was defined as high ligation (HL) versus CVL based on operative reports and videos. Two blinded radiologists independently evaluated the pre- and postoperative CT scans for radiographically abnormal nodes.

RESULTS

Of 197 patients who underwent CME, HL was performed in 56 (28%) and CVL in 141 (72%). There were no baseline differences in age, sex, body mass index, American Society of Anesthesiologists score or pathological staging, and there were no major intra-operative complications in either group (including no major vascular injuries). The median total number of nodes retrieved was 27 and 31 (P = 0.011) in HL and CVL groups, resepctively, with pathologically positive nodes identified in 33.9% and 39.8% (P = 0.704), respectively. Preoperative imaging identified abnormal cN3 nodes in 1.5% of patients; all of whom underwent CVL. No abnormal cN2 or cN3 nodes remained on postoperative imaging. The 60-day mortality was 0.5%, and major morbidity was 4%. One patient (0.5%) had an anastomotic recurrence after a median follow-up of 22 months.

CONCLUSION

With imperfect preoperative clinical nodal staging, and in the absence of randomized data, the low morbidity and oncological outcomes observed support the approach of CME with HL as a minimum standard, with CVL (D3 lymphadenectomy) in selected cases.

Urinary excretion of arsenic following rice consumption

Patterns of arsenic excretion were followed in a cohort (n = 6) eating a defined rice diet, 300 g per day d.wt. where arsenic speciation was characterized in cooked rice, following a period of abstinence from rice, and other high arsenic containing foods. A control group who did not consume rice were also monitored. The rice consumed in the study contained inorganic arsenic and dimethylarsinic acid (DMA) at a ratio of 1:1, yet the urine speciation was dominated by DMA (90%). At steady state (rice consumption/urinary excretion) ∼40% of rice derived arsenic was excreted via urine. By monitoring of each urine pass throughout the day it was observed that there was considerable variation (up to 13-fold) for an individual's total arsenic urine content, and that there was a time dependent variation in urinary total arsenic content. This calls into question the robustness of routinely used first pass/spot check urine sampling for arsenic analysis.

Isolated small uterine arteries from non-pregnant and term pregnant rats exhibit regulatory responses to elevations in extravascular pressure

An adequate blood supply is essential for the maintenance of uterine function and fetal health during parturition. However, labouring uterine contractions will impart compressive forces on small uterine arteries (SUA). We demonstrate that isolated, pressurised rat SUA arteries, pre-constricted with arginine vasopressin or high potassium solution, exhibit regulatory responses to elevations in extravascular pressure (EVP) which maintain internal diameter constant at EVPs of 0-40 mm Hg. This response is endothelium independent and is not modulated by pregnancy. No regulation was observed in calcium free solution. SUA myogenic responses to elevated EVP likely represents a mechanism for limiting reductions in uterine blood flow during uterine contraction.

Measurement of the 18Ne(α,p0) 21Na reaction cross section in the burning energy region for x-ray bursts

The 18Ne(α,p) 21Na reaction provides one of the main HCNO-breakout routes into the rp process in x-ray bursts. The 18Ne(α,p0) 21Na reaction cross section has been determined for the first time in the Gamow energy region for peak temperatures T∼2  GK by measuring its time-reversal reaction 21Na(p,α) 18Ne in inverse kinematics. The astrophysical rate for ground-state to ground-state transitions was found to be a factor of 2 lower than Hauser-Feshbach theoretical predictions. Our reduced rate will affect the physical conditions under which breakout from the HCNO cycles occurs via the 18Ne(α,p) 21Na reaction.

Microarray analysis of LTR retrotransposon silencing identifies Hdac1 as a regulator of retrotransposon expression in mouse embryonic stem cells

Retrotransposons are highly prevalent in mammalian genomes due to their ability to amplify in pluripotent cells or developing germ cells. Host mechanisms that silence retrotransposons in germ cells and pluripotent cells are important for limiting the accumulation of the repetitive elements in the genome during evolution. However, although silencing of selected individual retrotransposons can be relatively well-studied, many mammalian retrotransposons are seldom analysed and their silencing in germ cells, pluripotent cells or somatic cells remains poorly understood. Here we show, and experimentally verify, that cryptic repetitive element probes present in Illumina and Affymetrix gene expression microarray platforms can accurately and sensitively monitor repetitive element expression data. This computational approach to genome-wide retrotransposon expression has allowed us to identify the histone deacetylase Hdac1 as a component of the retrotransposon silencing machinery in mouse embryonic stem cells, and to determine the retrotransposon targets of Hdac1 in these cells. We also identify retrotransposons that are targets of other retrotransposon silencing mechanisms such as DNA methylation, Eset-mediated histone modification, and Ring1B/Eed-containing polycomb repressive complexes in mouse embryonic stem cells. Furthermore, our computational analysis of retrotransposon silencing suggests that multiple silencing mechanisms are independently targeted to retrotransposons in embryonic stem cells, that different genomic copies of the same retrotransposon can be differentially sensitive to these silencing mechanisms, and helps define retrotransposon sequence elements that are targeted by silencing machineries. Thus repeat annotation of gene expression microarray data suggests that a complex interplay between silencing mechanisms represses retrotransposon loci in germ cells and embryonic stem cells.

Systemic chemotherapy and surgical cytoreduction for poorly differentiated and signet ring cell adenocarcinomas of the appendix

BACKGROUND

Poorly differentiated and signet ring cell adenocarcinomas of the appendix represent a subset with aggressive tumor biology and poor outcomes with few studies evaluating the impact of systemic chemotherapy and cytoreductive surgery (CRS).

PATIENTS AND METHODS

A retrospective chart review of patients with either poorly differentiated and signet ring cell appendiceal adenocarcinomas was completed from 1992 to 2010.

RESULTS

One hundred forty-two patients were identified. Seventy-eight patients with metastatic disease received chemotherapy. Radiographic response was 44%, median progression-free survival (PFS) was 6.9 months, and median overall survival (OS) was 1.7 years. In multivariate analysis, response to chemotherapy [hazard ratio (HR) 0.5; P = 0.02] predicted improved PFS, and complete CRS (HR 0.3; P = 0.004) predicted improved OS. Patients who underwent complete CRS (n = 26) had a median relapse-free survival (RFS) of 1.2 years and a median OS of 4.2 years. In multivariate analysis for this subset, complete cytoreduction score of 0 was significantly correlated with improved RFS (HR 0.07; P = 0.01) and OS (HR 0.02; P = 0.01).

CONCLUSIONS

Systemic chemotherapy appears to be a viable treatment option for patients with metastatic poorly differentiated and signet ring cell appendiceal adenocarcinomas. Complete CRS is associated with improved RFS and OS, though part of this benefit likely reflects the selection of good tumor biology.

Mucinous appendiceal tumors of uncertain malignant potential (UMP): Prognostic factors and implications for treatment and follow-up

372

Background: The diagnosis of UMP is used for dysplastic mucinous tumors that are difficult to classify as clearly benign or malignant. Given the rarity of this tumor, management of these patients is unclear.

Methods: All patients with a pathologic diagnosis of an appendiceal mucinous UMP who underwent evaluation at a single institution between September 1993 and July 2009 were retrospectively reviewed. Patient demographics, operative findings, pathology, tumor markers, procedures performed, recurrence, overall survival, and disease-free survival were determined.

Results: Of 688 patients with appendiceal neoplasms, 62 (9%) patients (pts) were identified as having UMP. Initial procedures included: appendectomy - 45, colectomy - 11, cytoreduction - 2, and other - 4. Median follow-up was 43.2 months (range 2-184 mos). Median overall survival (OS) was 11.5 years (range 2-184 mos). Median disease-free survival (DFS) has not been reached. There was a trend towards improved DFS in patients who are: female, < 65 years of age, or have mucin confined to the appendix or its serosal surface. Clinicopathologic factors associated with a significantly worse overall DFS included elevated serum CEA (3.6 years, p = 0.0129) and CA-125 (4.16 years, p = 0.0288). DFS at 8 years follow-up in patients with a normal CEA was as follows: 100% if mucin confined to lumen of the appendix, 90% if mucin confined to serosa, and 69% if mucin was in an extra-appendiceal location. 15 patients developed recurrent disease and had an OS of 4.6 years after recurrence.

Conclusions: Mucinous UMP tumors of the appendix have an overall favorable prognosis. In patients with a negative margin and mucin confined to the appendix or serosa, expectant management may be sufficient. Elevation of CEA or CA-125 may warrant closer monitoring or intervention. If confirmed in a larger cohort, these findings may have substantial implications for management of these patients.

No significant financial relationships to disclose.

SYCE2 is required for synaptonemal complex assembly, double strand break repair, and homologous recombination

Synapsis is the process by which paired chromosome homologues closely associate in meiosis before crossover. In the synaptonemal complex (SC), axial elements of each homologue connect through molecules of SYCP1 to the central element, which contains the proteins SYCE1 and -2. We have derived mice lacking SYCE2 protein, producing males and females in which meiotic chromosomes align and axes form but do not synapse. Sex chromosomes are unaligned, not forming a sex body. Additionally, markers of DNA breakage and repair are retained on the axes, and crossover is impaired, culminating in both males and females failing to produce gametes. We show that SC formation can initiate at sites of SYCE1/SYCP1 localization but that these points of initiation cannot be extended in the absence of SYCE2. SC assembly is thus dependent on SYCP1, SYCE1, and SYCE2. We provide a model to explain this based on protein–protein interactions.

The effects of operative delay on the relief of neuropathic pain after injury to the brachial plexus

We investigated the effect of delay before nerve repair on neuropathic pain after injury to the brachial plexus. We studied 148 patients, 85 prospectively and 63 retrospectively. The mean number of avulsed spinal nerves was 3.2 (1 to 5). Pain was measured by a linear visual analogue scale and by the peripheral nerve injury scale. Early repair was more effective than delayed repair in the relief from pain and there was a strong correlation between functional recovery and relief from pain.

Dazl binds in vivo to specific transcripts and can regulate the pre-meiotic translation of Mvh in germ cells

Gametogenesis is a complex process subject to strict controls at both levels of transcription and translation. Members of a family of conserved RNA-binding proteins encoded by the DAZ genes are required for the translational regulation of gene expression essential for this process. Although loss of DAZ family genes is associated with infertility in several organisms including humans, the identity of the transcripts regulated in vivo is unknown. Using a combination of immunoprecipitation and microarray analysis, we have identified a number of mRNAs that are bound by the murine Dazl protein both in vivo and in vitro. Sequence analysis shows that these transcripts contain binding sites for Dazl, which have been conserved during evolution between human, rat and mouse. We have focussed on mouse vasa homologue (Mvh), a gene that is essential for male gametogenesis, and show that Dazl stimulates translation via the Mvh 3'-UTR. Finally, we show that germ cells of Dazl null mice contain reduced levels of Mvh protein, indicating that Dazl-mediated regulation of Mvh translation is crucial for mammalian spermatogenesis.

Expression profiling of the developing testis in wild-type and Dazl knockout mice

Genetic understanding of male-factor infertility requires knowledge of gene expression patterns associated with normal germ cell differentiation. The mouse is one of the best models of mammalian fertility due to its well-characterized genetics and the existence of many infertile mutants both naturally occurring and experimentally induced. We used cDNA microarrays firstly to investigate normal gene expression in the wild-type (wt) testis and secondly to gain a better insight into the effect of the disruption of the Dazl gene on spermatogenesis. We constructed a cDNA microarray from a subtracted and normalized adult testis library and focused on six developmental time-points during the initial synchronous wave of spermatogenesis. The results suggest that in the wild-type testis, 89.5% of genes on our chip change expression dramatically during the time-course. To identify patterns in the gene-expression data, a k-means clustering algorithm and principal component analysis were used. In the Dazl knockout testes, the majority of genes remain at baseline levels of expression, because absence of Dazl has a severe effect on cell-types present in the testis. Although in the prepubescent Dazl-null mice the final point reached in germ cell development is the leptotene-zygotene stage, the microarray results suggest that lack of Dazl expression has a detectable effect on the mRNA complement of germ cells as early as day 5 when only type A spermatogonia are present. Mol. Reprod. Dev. 67: 26-54, 2004.

Absence of mDazl produces a final block on germ cell development at meiosis

The autosomal gene DAZL is a member of a family of genes (DAZL, DAZ, BOULE), all of which contain a consensus RNA binding domain and are expressed in germ cells. Adult male and female mice null for Dazl lack gametes. In order to define more precisely the developmental stages in germ cells that require Dazl expression, the patterns of germ cell loss in immature male and female wild-type (+/+, WT) and Dazl -/- (DazlKO) mice were analysed. In females, loss of germ cells occurred during fetal life and was coincident with progression of cells through meiotic prophase. In males, testes were recovered from WT and DazlKO males obtained before and during the first wave of spermatogenesis (days 2-19). Mitotically active germ cells were present up to and including day 19. Functional differentiation of spermatogonia associated with detection of c-kit positive cells did not depend upon expression of Dazl. RBMY-positive cells (A, intermediate, B spermatogonia, zygotene and preleptotene spermatocytes) were reduced in DazlKO compared with WT testes. Staining of cell squashes from day 19 testes with anti-gamma-H2AX and anti-SCP3 antibodies showed that germ cells from DazlKO males were unable to progress beyond the leptotene stage of meiotic prophase I. It was concluded that in the absence of Dazl, germ cells can complete mitosis, and embark on functional differentiation but that, in both sexes, progression through meiotic prophase requires this RNA binding protein.

Spermatogenesis in testes of Dazl null mice after transplantation of wild-type germ cells

Dazl knockout male mice are infertile because their germ cells are unable to complete the first meiotic prophase in the first wave of spermatogenesis and thereafter decrease in number due to a block at the A-aligned to A1 transition. The ability of the surviving somatic components of the testes to retain their function in the absence of mature germ cells was tested by injecting marked wild-type germ cell suspensions containing spermatogonial stem cells. Comparison of the frequency and extent of colonization of Dazl knockout testes with that of testes chemically depleted of germ cells showed little if any difference. It was concluded that Dazlko testes seem unimpaired in their ability to support spermatogenesis. Therefore, Dazlko testes provide a useful and reliable recipient in which to evaluate spermatogonial stem cells. The results furthermore demonstrate that the somatic compartment of the testis of these animals retains functionality.

Lead and arsenic in bones of birds of prey from Spain

The bones (humerus and/or femur) of 229 birds of prey from 11 species were analyzed for Pb and As to evaluate their exposure to Pb shot. The species with the highest mean Pb levels were red kite (Milvus milvus) and Eurasian griffon (Gyps fulvus), and the species with the lowest levels were Eurasian buzzard (Buteo buteo) and booted eagle (Hieraaetus pennatus). Red kite also had the highest mean As level, an element present in small amounts in Pb shot. Elevated bone Pb concentrations (>10 microg/g dry weight) were found in 10 birds from six species. Clinical signs compatible with lethal Pb poisoning and/or excessive bone Pb concentrations (>20 microg/g) were observed in one Eurasian eagle-owl (Bubo bubo), one red kite, and one Eurasian griffon. Pb poisoning has been diagnosed in eight upland raptor species in Spain to date.

Loss of oocytes in Dazl knockout mice results in maintained ovarian steroidogenic function but altered gonadotropin secretion in adult animals

Within 2 days of birth, the mouse ovary is mainly composed of oocytes surrounded by a few pregranulosa cells forming primordial follicles that remain quiescent until they are recruited by intraovarian or other unknown factors to initiate growth of the oocyte and proliferation of the attendant granulosa cells. However, the role of the oocyte in this early development and organization of the follicle is poorly understood. The Dazl knockout (-/-) mouse in which there is total ablation of oocytes in fetal life has allowed us to address this issue. Ovaries from -/- females lack any follicular structure and have no cells positive for either Mullerian inhibiting factor or sulfated glycoprotein-1, indicating a lack of small follicles or corpora lutea. However, by immunocytochemistry, there are cells positive for 3beta-hydroxysteroid dehydrogenase, 17alpha-hydroxylase, and aromatase, indicating the presence of steroidogenically active cells capable of producing estrogen. This was confirmed by the presence of hypertrophied uterine endometrium expressing both estrogen receptor alpha (ER alpha) and ER beta together with normal levels of plasma estradiol. In addition, these steroidogenically active cells contain ER beta, inhibin alpha, and betaB-subunits, and -/- mice have low measurable plasma inhibin A and B levels. The ovarian steroids and inhibins had no significant effect on either plasma or pituitary gonadotropin levels, with significantly (P < 0.01) lower LH and FSH in intact +/+ and +/- females. However, significantly (P < 0.05) increased plasma inhibin B together with significantly (P < 0.05) lower FSH were observed in the +/- females. In conclusion, our data showed that despite oocyte loss in fetal life, the adult ovaries contained steroidogenically active cells capable of producing estradiol and inhibin. Furthermore, in the +/- mice, the enhanced plasma inhibin B implies a role for Dazl protein within the oocyte either from more small follicles or increased inhibin B production from each follicle.

A human DAZ transgene confers partial rescue of the mouse Dazl null phenotype

In a subset of infertile men, a spectrum of spermatogenic defects ranging from a complete absence of germ cells (sertoli cell only) to oligozoospermia is associated with microdeletions of the DAZ (deleted in azoospermia) gene cluster on human distal Yq. DAZ encodes a testis-specific protein with RNA-binding potential recently derived from a single-copy gene DAZL1 (DAZ-like) on chromosome 3. Y chromosomal DAZ homologues are confined to humans and higher primates. It remains unclear which function unique to higher primate spermatogenesis DAZ may serve, and the functional status of the gene recently has been questioned. To assess the extent of functional conservation we have tested the capacity of a human DAZ gene contained in a 225-kb yeast artificial chromosome to complement the sterile phenotype of the Dazl null mouse (Dazl-/-), which is characterized by severe germ-cell depletion and meiotic failure. Although Dazl-/- mice remained infertile when the DAZ transgene was introduced, histological examination revealed a partial and variable rescue of the mutant phenotype, manifest as a pronounced increase in the germ cell population of the seminiferous tubules and survival to the pachytene stage of meiosis. As well as constituting definitive proof of the spermatogenic role of the DAZ gene product, these findings confirm the high degree of functional conservation between the DAZ and DAZL1 genes, suggesting they may constitute a single target for contraceptive intervention and raising the possibility of therapeutic up-regulation of the DAZL1 gene in infertile men.

The mouse Dazla gene encodes a cytoplasmic protein essential for gametogenesis

RBM and DAZ/SPGY are two families of genes located on the Y chromosome that encode proteins containing RNA-binding motifs, and both have been described as candidate human spermatogenesis genes. Transmission of deletions from father to son has been observed in the case of DAZ, but neither gene family has been shown to be essential for spermatogenesis in human males. The DAZ/SPGY genes are particularly amenable to a knockout approach, as they are found on the Y chromosome in Old World primates and apes, but in other mammals, they are represented only by an autosomal gene, DAZLA, which is also present in Old World primates and apes. It has also been shown that a Dazla homologue is essential for spermatogenesis in Drosophila. Here we show that Dazla protein is cytoplasmic in male and female germ cells, unlike the nuclear RBM protein. Disruption of the Dazla gene leads to loss of germ cells and complete absence of gamete production, demonstrating that Dazla is essential for the differentiation of germ cells.

Pain relief from preganglionic injury to the brachial plexus by late intercostal nerve transfer

We performed intercostal nerve transfer in 19 patients to relieve pain from preganglionic injury to the brachial plexus. The procedure was successful in 16 patients at a mean of 28.6 months (12 to 68) after the injury.

PAIN RELIEF FROM PREGANGLIONIC INJURY TO THE BRACHIAL PLEXUS BY LATE INTERCOSTAL NERVE TRANSFER

We performed intercostal nerve transfer in 19 patients to relieve pain from preganglionic injury to the brachial plexus. The procedure was successful in 16 patients at a mean of 28.6 months (12 to 68) after the injury.

Abolition of contractions in the myometrium by acidification in vitro

Uterine dystocia, often of unknown cause, remains one of the commonest causes of emergency caesarean section. We have tested the hypothesis that small acidic changes in pH, that can occur during labour contractions, can decrease contractions and contribute to dystocia. We simultaneously recorded intracellular pH (pHi) and force in human myometrium: acidification abolished contractions. Such effects of pHi on uterine contractile activity may be of clinical significance. Blood flow reduces during each uterine contraction; the resulting fall in pHi could lead to inefficient uterine action in some labours and failure to progress (ie, dystocia).

A comparison of the effects of intracellular and extracellular pH on contraction in isolated rat portal vein

1. The effects of changes in extracellular and intracellular pH on spontaneous contractile activity in isolated rat portal vein have been investigated. 2. Small strips of portal vein were loaded with the pH-sensitive fluorophore carboxy-SNARF and intracellular pH (pHi) and contraction were measured simultaneously at 37 degrees C. The tissue was superfused with oxygenated, Hepes-buffered solutions at pH 7.4. Intracellular pH was altered by isosmotic substitution of weak acids or bases. External pH (pHo) was altered by addition of strong acid or base to the solution. 3. The mean resting value of pHi was 7.06 +/- 0.03 (n = 28). Alteration of pHi led to changes in spontaneous activity. Addition of butyrate (20 mM) reduced pHi by 0.18 +/- 0.01 pH units (n = 8). Decreasing pHi produced an early, brief increase in contractile activity followed by a longer lasting decrease or even abolition of contraction. 4. Addition of 20 mM trimethylamine or NH4Cl increased pHi by around 0.2 pH units and produced an early transient decrease in contractile activity followed by a later maintained increase, both in frequency and magnitude. Removal of base produced a rapid rebound decrease in pHi which was associated with a further transient increase in contractile activity followed by decreased activity. The effects of base on both pHi and contraction were concentration dependent over the range investigated (2.5-30 mM). 5. Alteration of pHo produced a change in pHi in the portal vein. The pHi change was rapid compared to other non-vascular cells (about 1 min to half-maximal response).(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous measurement of intracellular pH and contraction in uterine smooth muscle

Changes in intracellular pH (pHi) are thought to produce large changes in force production in the uterus. There have however, been no simultaneous measurements of pHi and force in the uterus and therefore no direct information is available about the relation between the two. We have used carboxy-SNARF (a pH-sensitive fluorophore) in small strips of longitudinal myometrium and obtained simultaneous measurements of pHi and force. SNARF did not alter contractile function, and continuous measurements of pHi could be made for 2 hours. The mean resting pHi (7.16) was similar to that reported previously. Application of weak bases rapidly raised pHi, in a concentration-dependent manner, followed by a gradual restoration of pHi to resting levels. Alkalinization greatly increased the frequency of contractions, often accompanied by a small increase in their amplitude. Removal of base produced a rebound acidification which transiently abolished contractions. Direct acidification of the cytoplasm, by application of weak acid, also abolished contractions. However the alkalinization which accompanied removal of acid, produced variable effects on force.

A simplified Prussian blue technique

The object of this study was to determine the sensitivity of magnetic resonance (MR) for imaging intracranial lesions with heavily T2-weighted images compared with that of computed tomographic (CT) and T1-weighted images. Fifty-five patients with known intracranial pathology consisting of primary neurogenic tumors, brain infarcts, demyelinating disease, and metastases were studied by MR and CT. Patients were studied with either 0.6 or 1.5 T systems with T1- and T2-weighted radiofrequency pulse sequences. The heavily T2-weighted images were found to be superior to the T1-weighted images in terms of sensitivity, with 168 lesions found versus 86 by CT and 104 by T1-weighted imaging.

DNaseI-hypersensitive sites at promoter-like sequences in the spacer of Xenopus laevis and Xenopus borealis ribosomal DNA

We have detected a DNAseI hypersensitive site in the ribosomal DNA spacer of Xenopus laevis and Xenopus borealis. The site is present in blood and embryonic nuclei of each species. In interspecies hybrids, however, the site is absent in unexpressed borealis rDNA, but is present normally in expressed laevis rDNA. Hypersensitive sites are located well upstream (over lkb) of the pre-ribosomal RNA promoter. Sequencing of the hypersensitive region in borealis rDNA, however, shows extensive homology with the promoter sequence, and with the hypersensitive region in X. laevis. Of two promoter-like duplications in each spacer, only the most upstream copy is associated with hypersensitivity to DNAaseI. Unlike DNAaseI, Endo R. MspI digests the rDNA of laevis blood nuclei at a domain extending downstream from the hypersensitive site to near the 40S promoter. Since the organisation of conserved sequence elements within this "proximal domain" is similar in three Xenopus species whose spacers have otherwise evolved rapidly, we conclude that this domain plays an important role in rDNA function.

Loss of rDNA methylation accompanies the onset of ribosomal gene activity in early development of X. laevis

The rRNA genes of Xenopus blood cells are heavily methylated, but there are two regions in the spacer that frequently contain unmethylated CpG. The undermethylated regions coincide with two regions containing a 60 nucleotide tandemly repeated sequence, and they are present in all somatic tissues that we have tested. Sperm rDNA, by contrast, is fully methylated at these sites in the spacer, and indirect evidence suggests that this may also be the case in oocytes. Loss of methyl groups occurs progressively over the first 20 hr of development, the same period in which embryonic rRNA synthesis initiates and increases in rate.