Mitral regurgitation in acute heart failure: prevalence and response to treatment

 

Heart failure (HF) affects an estimated 90 000 people within the UK. As a consequence of ventricular remodelling, mitral regurgitation (MR) is common in patients with HF, further contributing to poor prognosis, frequent hospitalisation, and higher rates of mortality. Conventional treatment options include medical therapy, cardiac resynchronisation and conventional mitral valve surgery, with transcatheter mitral valve repair (TMVR) reserved for symptomatic patients with left ventricular dysfunction and multiple comorbidities, considered high surgical risk.

Aim

Our objectives were to determine: (1) the proportion of patients with an acute HF admission, ejection fraction (EF) of <50% and moderate or more MR; (2) the effectiveness of optimal medical therapy (OMT) in reducing the severity of MR and symptoms; (3) the number of patients with moderate or more MR, EF <50% and symptoms despite OMT.

Method

We performed a retrospective analysis of patients who presented with acute HF to two large tertiary centres over a five-year period. Based on a combination of electronic care records, and national registry and mortality data, we determined baseline symptoms, symptom progression, and co-morbidities. Echocardiography data was used to assess the degree of MR and EF. Where patients underwent a subsequent echocardiogram on OMT, the change in the degree of MR, EF and symptoms (NYHA class) was examined.

Results

Over a five-year period (Jan 2012–Dec 2017), 1884 patients presented with acute HF. Of this cohort, 302 (16%) had moderate or more MR and EF of <50%. Mortality amongst patients with moderate or more MR was 29.9% at one year (compared to 26.9% for those with less than moderate MR, p=0.058). Of this cohort, 45% had sufficient clinical and echocardiographic paired follow up data to enable assessment of the effects of OMT (Age 78±20.78; Male n=76 (56.3%). This analysis showed, despite OMT, all 135 patients still had moderate or more MR. When compared with previous echocardiography data, 11 (8%) patients showed a reduction in the severity of MR which meant 92% (124) of patient with MR either saw no improvement or worsening of their MR severity. Of those with severe MR, 23% (7) demonstrated an improvement in the degree of MR following OMT. Clinically 70 (51.4%) patients had an improvement in symptoms. There was significant improvement in the NYHA class pre and post optimisation of medical therapy (p<0.001) across all grades of MR. Despite OMT, 124 (92%) patients with moderate or more MR and EF <50% remained symptomatic.

Conclusions

A large portion of patients who present with acute HF have moderate or more MR. Although medical therapy is effective in providing some relief from symptoms, the large majority of patients continue to have moderate or more MR. We propose a portion of these patients are potential candidates for TMVR, and should be considered for further intervention.

Funding Acknowledgement

Type of funding source: None

Development of a method to measure plasma and whole blood choline by liquid chromatography tandem mass spectrometry

Background

Current gold standard markers for myocardial damage are troponins I and T, which are both sensitive and specific for the detection of myocardial infarction, but require up to 6 h to become reliably elevated in serum. Investigation into markers with potential to identify patients with early ischaemic changes is therefore intense. Choline is reported to be prognostic in patients presenting with acute coronary syndromes via its release from ischaemic cell membranes.

Methods

Liquid chromatography tandem mass spectrometry was used to develop a method to quantitate choline in plasma and blood. The method involves addition of a deuterated internal standard to an aliquot of plasma or blood followed by organic solvent addition, which precipitates the proteins in the sample. Preparation was carried out directly into a 96-deep-well plate. Chromatography of choline used a strong cation exchange column and separation used a Waters Atlantis dC18 analytical column positioned directly before the mass spectrometer source, allowing on-line preanalytical clean up of the sample.

Results

The lower limit of quantitation was 0.38 μmol/L, linearity was observed up to 754 μmol/L, with a working concentration range of 0.38–224 μmol/L, inter- and intra-assay coefficients of variation were <6% and <4%, respectively. Samples were stable throughout five freeze–thaw cycles and recovery was between 94% and 114%.

Conclusions

The assay was successfully validated in accordance with FDA guidelines and is suitable for quantitation of choline in research and clinical settings.

Can a modified thrombolysis in myocardial infarction risk score outperform the original for risk stratifying emergency department patients with chest pain?

BACKGROUND

The thrombolysis in myocardial infarction (TIMI) risk score has been shown to risk stratify patients with suspected acute coronary syndromes (ACS) effectively in the emergency department (ED) but cannot be used to guide patient disposition. We aimed to evaluate whether modifying the TIMI risk score to give greater weighting to ischaemic ECG changes and troponin elevations would enhance its risk stratification and thus potentially facilitate safe patient discharge after 12-h troponin testing.

METHODS

A prospective diagnostic cohort study was performed within the ED at Manchester Royal Infirmary, a university-affiliated teaching hospital with an annual ED census of approximately 145,000 patients. 804 patients who had presented to the ED with suspected cardiac chest pain were recruited. All patients underwent 12-h troponin T testing and were followed up by telephone and chart review after 30 days for the composite primary outcome of death, acute myocardial infarction (AMI) or urgent coronary revascularisation.

RESULTS

The modified TIMI risk score outperformed the original (area under the receiver operator characteristic curve 0.87 versus 0.77, p<0.001). Using a cut-off of more than 2 points the score had a sensitivity of 96.4% for the prediction of 30-day events. The specificity of the score was only 51.0%, suggesting that in practice over 40% of patients would be ineligible for discharge even after troponin testing.

CONCLUSIONS

Modifications to the TIMI risk score can improve its performance in the risk stratification of patients presenting to the ED with chest pain. However, a lack of specificity may still limit its use for guiding patient disposition after troponin testing.

Early changes in the haemostatic and procoagulant systems after chemotherapy for breast cancer

Venous thromboembolism (VTE) following breast cancer chemotherapy is common. Chemotherapy-induced alterations in markers of haemostasis occur during chemotherapy. It is unclear how rapidly this occurs, whether this is upregulated in patients developing VTE and whether changes predict for VTE. Markers of haemostasis, functional clotting assays and vascular endothelial growth factor were measured before chemotherapy and at 24 h, 4 days, 8 days and 3 months following commencement of chemotherapy in early and advanced breast cancer patients and in age- and sex-matched controls. Duplex ultrasound imaging was performed after 1 month or if symptomatic. Of 123 patients, 9.8% developed VTE within 3 months. Activated partial thromboplastin time (APTT), prothrombin time (PT), D-dimer, fibrinogen, platelet count, VEGF and fibrinogen were increased in cancer. Fibrinogen, D-dimer, VEGF and tissue factor were increased, at baseline, in patients subsequently developing VTE. D-dimer of less than 500 ng ml⁻¹ has a negative predictive value of 97%. Activated partial thromboplastin time, PT and thrombin–antithrombin showed significantly different trends, as early as within 24 h, in response to chemotherapy in patients subsequently developing VTE. Markers of coagulation and procoagulants are increased, before chemotherapy, in patients who subsequently develop VTE. A group of patients at minimal risk of VTE can be identified, allowing targeted thrombopropylaxis to the higher risk group.

Angiogenic characteristics of circulating and tumoural thrombospondin-1 in breast cancer

In cancer models, thrombospondin-1 (TSP-1) has been shown to inhibit angiogenesis or promote metastasis by increasing adhesion of malignant cells to endothelium. To determine the role of TSP-1 in breast cancer and breast cancer angiogenesis, we have measured TSP-1 in plasma and tumour cytosols and compared levels to established clinicopathological prognostic parameters and intratumoural microvessel density. TSP-1 was measured, by radioimmunoassay, in plasma (pTSP-1) and tumour cytosols (cTSP-1) of women with early breast cancer (EBC) (n=71). pTSP-1 in EBC was compared to pTSP-1 levels in women with advanced breast cancer (ABC) (n=66), normal controls (n=77) and was correlated with prognostic features and microvessel density (MVD) (measured by CD31 immunostaining). cTSP-1 levels were compared to prognostic features and microvessel density. pTSP-1 in women with EBC (median 484, IQR 344-877 ng/ml) and ABC (median 588, IQR 430-952 ng/ml) were elevated when compared to normal controls (median 21, IQR 175-247) (p<0.001). Women with lymph node metastases (n=35) had higher levels of TSP-1 (median 799 ng/ml, IQR 455-943) than women who were node negative (median 343 ng/ml, IQR 267-514) (n=36) (p<0.05). Levels of pTSP-1 in EBC correlated with MVD (R=0.39, p<0.05). Levels of TSP-1 in tumour cytosols of women with EBC (median 1714, IQR 893-5283 ng/ml) correlated with microvessel density (R=0.46, p<0.01). Circulating levels of TSP-1 appear to be a marker of breast cancer aggressiveness and in breast cancer may have a pro-angiogenic rather than anti-angiogenic role.

Serum vascular endothelial growth factor in breast cancer

Many studies have reported elevated serum concentrations of vascular endothelial growth factor (VEGF) in patients with cancer and claimed that the measurement of circulating VEGF is a surrogate marker of angiogenesis and/or metastasis. To determine the value of VEGF measurement in the diagnosis and prognosis of breast cancer, we measured levels in women with and without breast cancer. Platelet-depleted plasma VEGF levels were measured in premenopausal women at four-day intervals across the menstrual cycle, postmenopausal women and postmenopausal women who had undergone hysterectomy. Platelet-depleted plasma VEGF was also measured in pre- and postmenopausal women with early breast cancer (EBC) and levels compared with intratumoral levels, clinicopathological prognostic parameters and microvessel density. Levels of VEGF were determined using ELISA and immuno-histochemistry. Microvessel density was determined by immunohistochemical CD34 staining. Plasma VEGF in premenopausal women remained stable across the menstrual cycle except for a peak between days 8 and 12. VEGF levels in postmenopausal women were higher than in premenopausal women unless postmenopausal women had undergone hysterectomy. Amongst premenopausal women, levels of VEGF were high in 22 EBC patients when compared to normal premenopausal controls. No correlation was found between plasma and intratumoral VEGF, clinicopathological prognostic parameters or tumour microvessel density. The origin of circulating VEGF differs between pre- and postmenopausal women. Its measurement is unlikely to provide clinically useful diagnostic and prognostic information in women with early and advanced breast cancer.

Prevention of venous thromboembolism in surgical patients with breast cancer

Background

No randomized trial has yet studied venous thromboembolism (VTE) prophylaxis in patients undergoing surgery for breast cancer.

Methods

Relevant articles were identified using Medline searches. Secondary articles were identified from the reference lists of key papers.

Results and conclusion

The absence of randomized trials comparing different methods of VTE prophylaxis with controls makes an evidence-based consensus among breast cancer surgeons difficult. Intermittent pneumatic compression (IPC) and graduated compression (GC) are effective in reducing VTE without the haemorrhagic complications associated with heparin; their effects are additive. The authors suggest the following strategy. All patients undergoing surgery for breast cancer should receive both IPC and GC, with heparin reserved for those at very high risk. A controlled trial should randomize women to receive heparin or not, and all women should have both IPC and GC. The primary endpoints should be the development of VTE and/or haemorrhagic complications.

Fetal gonadotrope cell origin of FSH-secreting pituitary adenoma - insight into human pituitary tumour pathogenesis

OBJECTIVE

The pathogenesis of human pituitary adenomas remains unclear, but we report a case of FSH-secreting pituitary adenoma whose monohormonal phenotype suggests it was of fetal origin.

PATIENTS

A 28-year-old woman presented with abdominal discomfort and irregular menses, enlarged multicystic ovaries and elevated serum oestradiol, with sustained high-normal FSH and low LH levels.

MEASUREMENTS

Endocrine studies were performed before and after curative surgery, with assessment of tumour hormone secretion in vitro, and immunostaining of tumour tissue for a series of gonadotrope proteins.

RESULTS

Immunocytochemistry showed that tumour cells were monohormonal for FSH. Normal components of gonadotrope signalling pathways were expressed, including oestrogen receptor-alpha, activin receptors, secretogranin-II and chromogranin-A. beta-glycan, the putative inhibin coreceptor, was absent. Tumour culture in vitro confirmed secretion of FSH with minimal LH, that was unsuppressed by oestradiol or inhibin-A. Human fetal pituitary tissue contained FSH-only cells at 18 weeks gestation, whereas normal adult pituitary tissue contained only bihormonal gonadotropes.

CONCLUSIONS

We propose that this pituitary adenoma represents an indolent tumour of monohormonal fetal gonadotrope cells that originated early in gestation. Pituitary tumours may therefore arise from abnormal persistence of fetal cell types, with extremely slow growth over many years until reaching a size threshold to generate an endocrine syndrome. Understanding fetal pituitary architecture and function may be more informative for new insights into pituitary tumour pathogenesis than classical theories of cancer biology that invoke unrestrained cell proliferation.

Alteration in platelet function in patients with early breast cancer

The aim of this study was to examine our hypothesis that platelets of patients with breast cancer were functionally altered compared to healthy controls. The results have shown that the platelets from women with early breast cancer released significantly more vascular endothelial growth factor (VEGF) when stimulated with thrombin, tissue factor, clotting, or over a period of time. Similarly, release of thrombospondin (TSP) with thrombin and tissue factor was higher, but failed to reach a significant level. Thus, the observed differences in platelet response support our hypothesis, but warrant further work to determine the reason underlying the observed difference and potential clinical relevance of our findings.

The endopeptidase inhibitor, candoxatril, and its therapeutic potential in the treatment of chronic cardiac failure in man

Candoxatril (UK-79300) is the orally-active prodrug of candoxatrilat (UK-73967), the active enantiomer of (+/-)candoxatrilat (UK-69578), a potent neutral endopeptidase (NEP) inhibitor. This article describes the rationale behind the use of such a drug in the treatment of chronic heart failure in man. It further describes the pharmacokinetics and pharmacodynamics of candoxatril in normal healthy individuals and in patients with chronic cardiac failure. In addition, we describe the initial results comparing candoxatril with furosemide and captopril in human heart failure.

Plasma concentrations of tumour dimeric pyruvate kinase are increased in patients with chronic cardiac failure

BACKGROUND

The aim of the study was to assess the effect of chronic cardiac failure (CCF) on circulating plasma concentrations of tumour metabolic marker dimeric pyruvate kinase type M2 (M2-PK).

METHODS

Fifty patients with clinically stable CCF were studied. Patients with a history of past or ongoing malignancy were excluded. Dimeric M2-PK was measured by enzyme-linked immunosorbent assay in EDTA plasma.

RESULTS

Dimeric M2-PK concentration increased significantly (P = 0.005) with increasing clinical severity of CCF as assessed by the New York Heart Association classification grade.

CONCLUSIONS

Chronic cardiac failure results in an increased circulating plasma concentration of M2-PK, probably related to increased glycolytic flux. The physiological significance of the results is at present unclear but may relate to maintaining a balance between energy production and the supply of glycolytic intermediates to maintain synthetic processes. The results of this investigation will also have significance in the clinical interpretation of M2-PK concentrations.

Variability of Nt-proANP and C-ANP

BACKGROUND

Natriuretic peptides are frequently measured in patients with chronic cardiac failure (CCF). We set out to compare the variability of atrial natriuretic peptide (C-ANP) and its precursor N-terminal pro-ANP (Nt-proANP) to decide which would be more suitable for routine use.

METHODS

Ten males with compensated CCF (age range 62-76 years) were studied, with matched controls. Blood was withdrawn every 2 min for 90 min from a forearm vein, and plasma C-ANP and Nt-proANP were measured by radioimmunoassay.

RESULTS

Levels were elevated in the patient group [C-ANP: median 268 (range 171-423) vs. 40 (28-56) ng L-1, P < 0.0002 Mann-Whitney U-test; Nt-proANP: 1955 (562-4451) vs. 621 (409-961) pmol L-1, P < 0.003]. A similar number of 'peaks' was observed in both groups with both peptides, about one every 10 min, and their relative height was similar in both groups. Variability was greater for C-ANP than for Nt-proANP in both patients [coefficient of variation of means 51 (range 36-70) vs. 3.6 (2.1-6.2)%, P < 0.01; sign test] and controls [65 (49-83) vs. 8.9 (4.7-13.5)%, P < 0.01].

CONCLUSION

Nt-proANP is less variable than C-ANP and hence more suited for diagnostic or prognostic use.

The sensitivity of the assessment process in screening mammography

A follow-up of 3143 women from four screening centres, who were assessed after screening mammography, showed that 371 had breast cancer diagnosed at that assessment and 62 developed a breast cancer in the following 6 years. Of these, 32 were judged to be false-negatives at assessment, with 23 of the 32 at the site originally suspected. The results show that the assessment process is not infallible and that the scale of the problem only becomes clear when an exhaustive search is made for missed cancers.

Comparative physiological study of arbutamine with exercise in humans

Pharmacological stress testing may be used in the diagnosis of coronary artery disease when there are contra-indications to the use of conventional exercise protocols. The responses to such testing using arbutamine and to conventional treadmill exercise were compared in eight patients. Respiratory gas analysis and cardiovascular observations were performed during both tests. For an equivalent increment in heart rate, both protocols increased systolic blood pressure and serum lactate. Minute ventilation and oxygen consumption also rose during both protocols, but much more so with exercise. The end-tidal partial pressure of CO(2) [35.1 (S.D. 3. 1) to 30.8 (6.6) mmHg] and the dead space/tidal volume ratio (V(D)/V(T)) [0.37 (0.09) to 0.33 (0.08)] fell significantly during arbutamine infusion, but the respiratory exchange ratio did not change during either protocol. Oxygen pulse, a marker of stroke volume, did not change significantly after arbutamine, but rose markedly after exercise [arbutamine, 3.9 (1.1) to 3.37 (0.7) ml. min(-1).beat(-1); exercise, 4.7 (1.4) to 16.1 (4.6) ml.min(-1). beat(-1) (P<0.0001 compared with baseline); difference between peak responses: P<0.0001]. We conclude that arbutamine simulates some of the physiological responses to exercise, although a number of these responses are less marked than during conventional exercise, in particular cardiac output (oxygen pulse). An increase in ventilation is produced, possibly due to direct stimulation of arterial chemoreceptors. These data suggest that the main action of arbutamine is to increase central drive rather than to establish peripheral demand.

Is the secretion of atrial natriuretic peptide in man under neural control?

AIMS

Previous work has described short-term variation in the circulating plasma level of atrial natriuretic peptide (ANP), but the mechanism remains unknown. Our aim was to investigate the role of cardiac innervation in this variability.

METHODS AND RESULTS

Blood samples were obtained from the right atrium via a pulmonary artery flotation catheter every 2 min over a 90 min period. Seven patients who underwent cardiac transplantation by the standard biatrial technique (partial innervation) and ten patients who underwent transplantation by the bicaval technique (total denervation) were studied. ANP levels were measured by radioimmunoassay. The median ANP levels were somewhat higher in the biatrial group compared to the bicaval group [470 (150-1095) vs. 216 (100-605) pg. ml(-1); median (range); P = ns], and both were much higher than normal levels in the pulmonary artery (40 (24, 56) pg ml(-1); median and interquartile range). In both transplant groups circulating plasma ANP levels showed considerable variability. The median number of 'peaks' and 'troughs', as counted by visual inspection, were not significantly different between the two groups. Computer analysis identified 12-16 and 6-15 'pulses' in the biatrial and bicaval group, respectively. Further analysis revealed that pulse amplitude, height and area were significantly higher in the biatrial compared to the bicaval group.

CONCLUSION

It would appear that variability of circulating plasma levels of ANP is preserved despite complete or partial cardiac denervation, and so a neural mechanism does not appear to account for such variation.

Exhaled nitric oxide during incremental and constant workload exercise in chronic cardiac failure

BACKGROUND

Nitric oxide (NO) is present in exhaled breath and produced by the pulmonary vascular endothelium as a potent vasodilator. Exercise is normally associated with pulmonary vasodilatation and a decrease in pulmonary vascular resistance to accommodate the increase in cardiac output. If production of NO is impaired in patients with chronic congestive cardiac failure (CCF), this might contribute to their exercise intolerance.

PATIENTS AND METHODS

We quantified NO production (V NO) in 12 patients with chronic stable CCF and 12 controls, at rest and during incremental cardiopulmonary exercise on a treadmill, and at a later date during constant workload exercise.

RESULTS

Patients had reduced V NO compared with controls during incremental exercise [381 (180) vs. 777 (275) nL min-1; mean (SD); P < 0.0001] but at constant workload V NO was similar between the two groups [353 (124) vs. 389 (189) nL min-1; P = 0.25]. Plasma levels of nitrate, the stable end-product of NO production, were significantly higher in patients [resting value 46.1 (21.6) vs. 23.0 (10.0) microM; P = 0.004] and were not influenced by exercise.

CONCLUSION

Impaired NO-mediated pulmonary vasodilatation does not appear to contribute to exercise limitation in CCF. Alternatively, the lower NO production observed during maximal exercise in the patient group compared with controls may reflect a reduced incremental response of a system that is already abnormally activated in heart failure.

The genomic region encompassing the nephropathic cystinosis gene (CTNS): complete sequencing of a 200-kb segment and discovery of a novel gene within the common cystinosis-causing deletion

Nephropathic cystinosis is an autosomal recessive disorder caused by the defective transport of cystine out of lysosomes. Recently, the causative gene (CTNS) was identified and presumed to encode an integral membrane protein called cystinosin. Many of the disease-associated mutations in CTNS are deletions, including one >55 kb in size that represents the most common cystinosis allele encountered to date. In an effort to determine the precise genomic organization of CTNS and to gain sequence-based insight about the DNA within and flanking cystinosis-associated deletions, we mapped and sequenced the region of human chromosome 17p13 encompassing CTNS. Specifically, a bacterial artificial chromosome (BAC)-based physical map spanning CTNS was constructed by sequence-tagged site (STS)-content mapping. The resulting BAC contig provided the relative order of 43 STSs. Two overlapping BACs, which together contain all of the CTNS exons as well as extensive amounts of flanking DNA, were selected and subjected to shotgun sequencing. A total of 200,237 bp of contiguous, high-accuracy sequence was generated. Analysis of the resulting data revealed a number of interesting features about this genomic region, including the long-range organization of CTNS, insight about the breakpoints and intervening DNA associated with the common cystinosis-causing deletion, and structural information about five genes neighboring CTNS (human ortholog of rat vanilloid receptor subtype 1 gene, CARKL, TIP-1, P2X5, and HUMINAE). In particular, sequence analysis detected the presence of a novel gene (CARKL) residing within the most common cystinosis-causing deletion. This gene encodes a previously unknown protein that is predicted to function as a carbohydrate kinase. Interestingly, both CTNS and CARKL are absent in nearly half of all cystinosis patients (i.e., those homozygous for the common deletion). [The sequence data described in this paper have been submitted to the GenBank data library under accession nos. AF168787 and AF163573.]

Ocular nonnephropathic cystinosis: clinical, biochemical, and molecular correlations

Ocular nonnephropathic cystinosis, a variant of the classic nephropathic type of cystinosis, is an autosomal recessive lysosomal storage disorder characterized by photophobia due to corneal cystine crystals but absence of renal disease. We determined the molecular basis for ocular cystinosis in four individuals. All had mutations in the cystinosis gene CTNS, indicating that ocular cystinosis is allelic with classic nephropathic cystinosis. The ocular cystinosis patients each had one severe mutation and one mild mutation, the latter consisting of either a 928 G-->A (G197R) mutation or an IVS10-3 C-->G splicing mutation resulting in the insertion of 182 bp of IVS10 into the CTNS mRNA. The mild mutations appear to allow for residual CTNS mRNA production, significant amounts of lysosomal cystine transport, and lower levels of cellular cystine compared with those in nephropathic cystinosis. The lack of kidney involvement in ocular cystinosis may be explained by two different mechanisms. On the one hand (e.g. the G197R mutation), significant residual cystinosin activity may be present in every tissue. On the other hand (e.g. the IVS 10-3 C-->G mutation), substantial cystinosin activity may exist in the kidney because of that tissue's specific expression of factors that promote splicing of a normal CTNS transcript. Each of these mechanisms could result in minimally reduced lysosomal cystine transport in the kidneys.

Identification and detection of the common 65-kb deletion breakpoint in the nephropathic cystinosis gene (CTNS)

The most common mutation in the cystinosis gene, CTNS, is a 65-kb deletion thought to have originated in Germany. Although homozygotes for this deletion are detectable by the absence of the D17S829 polymorphic marker, no method exists to identify heterozygotes. We identified the 65-kb deletion breakpoints and used flanking PCR primers to amplify a 423-bp fragment present only in the deletion alleles. Using this method, we determined that 121 of 216 (56%) cystinosis alleles examined bore the 65-kb deletion. We found no non-Europeans with the deletion, and the deletion size and breakpoints appeared identical in all patients studied, supporting the concept of a founder effect. The addition of D17S829 primers (266 bp apart) to the PCR created a multiplex PCR system useful for diagnosing cystinosis patients homozygous and heterozygous for the 65-kb deletion.

CTNS mutations in an American-based population of cystinosis patients

Nephropathic cystinosis is an autosomal recessive lysosomal storage disease characterized by renal failure at 10 years of age and other systemic complications. The gene for cystinosis, CTNS, has 12 exons. Its 2.6-kb mRNA codes for a 367-amino-acid putative cystine transporter with seven transmembrane domains. Previously reported mutations include a 65-kb "European" deletion involving marker D17S829 and 11 small mutations. Mutation analysis of 108 American-based nephropathic cystinosis patients revealed that 48 patients (44%) were homozygous for the 65-kb deletion, 2 had a smaller major deletion, 11 were homozygous and 3 were heterozygous for 753G-->A (W138X), and 24 had 21 other mutations. In 20 patients (19%), no mutations were found. Of 82 alleles bearing the 65-kb deletion, 38 derived from Germany, 28 from the British Isles, and 4 from Iceland. Eighteen new mutations were identified, including the first reported missense mutations, two in-frame deletions, and mutations in patients of African American, Mexican, and Indian ancestry. CTNS mutations are spread throughout the leader sequence, transmembrane, and nontransmembrane regions. According to a cystinosis clinical severity score, homozygotes for the 65-kb deletion and for W138X have average disease, whereas mutations involving the first amino acids prior to transmembrane domains are associated with mild disease. By northern blot analysis, CTNS was not expressed in patients homozygous for the 65-kb deletion but was expressed in all 15 other patients tested. These data demonstrate the origins of CTNS mutations in America and provide a basis for possible molecular diagnosis in this population.

Inherited disorders of glycoprotein synthesis: cell biological insights

Disorders of glycoprotein synthesis have been described only recently, and few have been studied extensively at both the clinical and biochemical level. The identification and characterization of these rare diseases are important, not only for the patients and their families, but because they offer enormous insight into biological processes. For example, the targeting of acid hydrolases to lysosomes by mannose-6-phosphate was discovered as a direct result of the elucidation of the defect in I-cell disease. The notion of carbohydrates as targeting agents continues to have ramifications today, with the success of macrophage-targeted enzyme replacement therapy for Gaucher disease. Likewise, confirmation of the in vivo role of fucose-containing glycans and selectins in neutrophil function came from studies using specimens from patients with leucocyte adhesion deficiency type II due to reduced availability of GDP-fucose. Identification of the in vivo ligands of selectins also has implications for anti-inflammatory therapies. Macular corneal dystrophy and spondyloepiphyseal dysplasia tarda offer an opportunity to investigate the number of different sulfotransferases in cells, their substrates, and their tissue expression. The Ehlers-Danlos progeroid variant offers insight into the function and regulation of the proteoglycan decorin, and suggests that several of the enzymes involved in proteoglycan synthesis may function as a multienzyme complex. The common occurrence of hypergonadotropic hypogonadism in patients with galactosemia or carbohydrate-deficient glycoprotein protein syndrome, due to defective N-linked glycosylation, suggests that ovarian function is particularly dependent on proper glycan-synthesis. A host of other concepts await discovery as a fuller contingent of human disorders of glycan synthesis achieves recognition.

Responses of atrial natriuretic peptide and brain natriuretic peptide to exercise in patients with chronic heart failure and normal control subjects

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are known to be elevated in patients with chronic heart failure at rest. While it is known that during exercise the circulating level of ANP increases in patients with heart failure, the response of BNP to exercise in these patients relative to control subjects is unclear. Ten patients with stable chronic heart failure and 10 normal control subjects performed symptom-limited exercise with respired gas analysis. All patients had depressed left ventricular ejection fractions (LVEF). Patients had lower peak oxygen consumption PVo2) than the control group [median (range) 1.18 (0.98-1.76) vs. 1.94 (1.53-2.31) L min-1; P < 0.001]. Circulating plasma levels of ANP and BNP were higher at rest in patients than in control subjects [ANP 335 (140-700) vs. 90 (25-500) pg mL-1; BNP 42 (25-50) vs. 20 (10-20) pg mL-1], and at peak exercise [ANP 400 (200-1000) vs. 130 (10-590); BNP 46 (40-51) vs. 20 (10-30)]. The rise in ANP at peak exercise was significant in patients compared with the resting level, but not in control subjects. For BNP, there was a significant rise in patients but no change in control subjects. The circulating plasma levels of both peptides showed a strong negative correlation with LVEF (ANP, P < 0.005; BNP, P < 0.0001) and, to a less extent, with RVEF. It is possible that BNP may give a better indication of cardiac function.

Stability of plasma concentrations of N- and C-terminal atrial natriuretic peptides at room temperature

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The effect of the neutral endopeptidase inhibitor drug, candoxatril, on circulating levels of two of the most potent vasoactive peptides

AIMS

Candoxatril is a specific neutral endopeptidase (NEP) 24.11 inhibitor, and previous work has documented the effect of NEP inhibition on atrial and brain natriuretic peptides (ANP, BNP). The aim of the present study was to ascertain the effect of NEP inhibition on circulating levels of vasoactive peptides.

METHODS

We studied seven patients with chronic heart failure who were randomized to receive candoxatril, candoxatril/captopril, captopril and placebo in a four way cross over, double-blind pattern.

RESULTS

The mean circulating level of endothelin (ET) was increased 2 h after placebo (10 to 20 pg ml-1) and also calcitonin gene-related peptide (CGRP) (27 to 51 pg ml-1), but ANP levels changed little during this time (73 to 75 pg ml-1). Following candoxatril, however, ET (10 to 39 pg ml-1, P < 0.05), CGRP (34 to 99 pg ml-1, P < 0.05) and ANP (72 to 108 pg ml-1, P < 0.05) increased further. A similar result was observed following combined treatment with candoxatril and captopril.

CONCLUSIONS

We conclude that neutral endopeptidase inhibition increases circulating plasma levels of ET and CGRP in addition to the natriuretic peptides.

Fine mapping of the cystinosis gene using an integrated genetic and physical map of a region within human chromosome band 17p13

The cystinosis gene has been reported to reside in a 3.1 cM region of chromosome 17p13 flanked by markers D17S1828 and D17S1798. We created a yeast artificial chromosome (YAC) contig between these markers and report here an integrated genetic and physical map which will aid in the identification of other genes in this area. Using one pertinent YAC clone, 898A10, we identified new polymorphic markers in the cystinosis gene region. One such marker, D17S2167, was localized by radiation hybrid analysis to within 10.2 cR8000 of D17S1828. Haplotype analysis in two separate informative families revealed recombination events which placed the cystinosis gene between markers D17S1828 and D17S2167, an area estimated to be 187-510 kb in size. This dramatic narrowing of the cystinosis gene region permits the creation of a P1 or cosmid contig across the area of interest. The ultimate cloning of the cystinosis gene should eventually reveal how a functional lysosomal transport protein is synthesized, targetted, processed, and integrated into the lysosomal membrane.

Neuroendocrine changes in chronic cardiac failure

Numerous hormonal and neuroendocrine changes have been described in patients with chronic cardiac failure. These affect the balance of vasodilator and vasoconstrictor factors in favour of the latter, to the detriment of the circulation. Whether this is a reaction to central cardiac (haemodynamic) abnormalities, or is an integral part of the syndrome of heart failure, remains to be determined. Catecholamine levels are increased, especially in severe heart failure, and contribute to the vasoconstriction and probably also to lethal ventricular arrhythmias. The renin-angiotensin-aldosterone system (RAAS) is also activated, causing fluid retention and further vasoconstriction. In the earlier stages, some of this increase may be iatrogenic due to the use of loop diuretics or inhibitors of angiotensin converting enzyme, but there is evidence for independent RAAS activation in more severe grades of heart failure. The role of vasoconstrictor peptides such as neuropeptide Y and endothelin is briefly considered. Counterbalancing these are vasodilator peptides, in particular atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP). The possibility of therapeutic interventions to increase circulating natriuretic hormone levels is discussed.

Experience with 105 patients with priapism: update review of all aspects

A 26-year experience with all aspects of priapism is reviewed in 105 children and adults. The etiology of the priapism was idiopathic or drug-induced, or owing to sickle cell disease, trauma, neoplasia, leukemia, papaverine-phentolamine injections and total parenteral alimentation. The pathophysiology of prolonged erection is discussed. Treatment is reviewed in respect to initial studies before the type of shunting procedure required is selected. Various shunt techniques are presented with outcome. Complications and their possible causes are discussed, and the importance of medicolegal risk is emphasized. Impotence is a common sequela of priapism.

Adriamycin-vitamin E combination therapy for treatment of prostate adenocarcinoma in the Nb rat model

Adriamycin used in combination with vitamin E (Tocopherol) was evaluated in the treatment of Nb rat prostate adenocarcinoma. Vitamin E has been shown to enhance the growth-inhibitory effects of adriamycin on human prostatic carcinoma cells in vitro. The adriamycin-vitamin E treatment groups had the lowest average final tumor volume, but the mortality rate was 57% (17/30). These results suggest that vitamin E may play a role in enhancing the cytotoxic effects of adriamycin, but may not have any protective effect on normal cells as previously suggested through in vitro methods.

Experimental continent diversion

Urinary diversion utilizing a continence-maintaining ileal valve has been performed in 12 canines. This procedure offers a simple surgical procedure and uses the diversion's internal fluid pressure to maintain continence. Of 12 canines with this continence-maintaining ileal valve, 11 remained continent at sacrifice. Operative complications were minimal and late complications occurred in 2 dogs. Histological evaluation of the diversionary tissues revealed slight changes in the mucosa of the ileal valve, with some flattening of the villi. This procedure may have a clinical role in urinary diversion for patients with pelvic malignancy or patients who need urinary diversion for other reasons.