Population-based study of sleep-disordered breathing as a risk factor for hypertension

BACKGROUND

Clinical observations have linked sleep-disordered breathing, a condition of repeated apneas and hypopneas during sleep, with hypertension but evidence for an independent association has been lacking. Understanding this relationship is important because the prevalence of sleep-disordered breathing is high in adults.

OBJECTIVE

To test the hypothesis that sleep-disordered breathing is related to elevated blood pressure independent of confounding factors.

METHODS

The sample included 1060 employed women and men aged 30 through 60 years who had completed an overnight protocol as part of the Wisconsin Sleep Cohort Study. In-laboratory polysomnography was used to determine sleep-disordered breathing status, quantified as the number of apneas and hypopneas per hour of sleep (apnea-hypopnea index). Blood pressure was measured on the night polysomnography was performed.

RESULTS

Blood pressure increased linearly with increasing apnea-hypopnea index (P = .003 for systolic, P = .01 for diastolic, adjusted for confounding factors). The magnitude of the linear association increased with decreasing obesity. At a body mass index (weight in kilograms divided by the square of the height in meters) of 30 kg/m2, an apnea-hypopnea index of 15 (vs 0) was associated with blood pressure increases of 3.6 mm Hg for systolic (95% confidence interval, 1.3-6.0) and 1.8 mm Hg for diastolic (95% confidence interval, 0.3-3.3). The odds ratio for hypertension associated with an apnea-hypopnea index of 15 (vs 0) was 1.8 (95% confidence interval, 1.3-2.4).

CONCLUSIONS

There is a dose-response relationship between sleep-disordered breathing and blood pressure, independent of known confounding factors. If causal, the high prevalence of sleep-disordered breathing could account for hypertension in a substantial number of adults in the United States.

Neonatal welfare and placental transfer of fentanyl and bupivacaine during ambulatory combined spinal epidural analgesia for labour

To investigate current concerns that potent opioid drugs, such as fentanyl, used for labour regional analgesia may affect neonatal status, maternal and umbilical plasma concentrations of fentanyl and bupivacaine at delivery were measured in 40 nulliparous patients receiving low-dose combined spinal epidural analgesia. Neonatal assessments included Apgar scores, umbilical blood gases and neurobehavioural tests. All maternal and umbilical venous plasma concentrations were low. Maternal and umbilical vein total fentanyl concentrations increased with increasing doses of epidural fentanyl (r = 0.46 and 0.30, respectively, p < 0.01). There were no significant differences between maternal and umbilical venous plasma total or free concentrations of fentanyl. Mean umbilical vein/maternal fentanyl ratios were 1.12 for total drug and 1.20 for free drug and values were unrelated to the last epidural bolus to delivery interval (r = 0.12, p = 0.49). There were no correlations between Apgar scores, umbilical blood gases or neurobehavioural scores and umbilical venous concentrations of either fentanyl or bupivacaine. The dose of fentanyl used for ambulatory combined spinal epidural analgesia would appear to have a negligible effect on neonatal condition.

Blood pressure and fetal heart rate changes with patient-controlled combined spinal epidural analgesia while ambulating in labour

OBJECTIVE

To determine the effect of patient-controlled combined spinal epidural analgesia (PCEA) on maternal pulse and blood pressure, and fetal heart rate in primigravid women, when adapting different positions in labour.

DESIGN

A prospective study.

SETTING

Queen Charlotte's and Chelsea hospital, London.

PARTICIPANTS

Fifty-five primigravid women in labour at > or = 37 weeks of gestation; 40 women had supervised standing top-ups given by an anaesthetist. A further 15 women had PCEA top-ups given in each of standing, sitting and lying positions.

MAIN OUTCOME MEASURES

Maternal pulse rate, blood pressure and fetal heart rate changes following epidural top-ups.

RESULTS

In the first 40 women there was no clinically significant fall in their blood pressure (< 5 mmHg). The subsequent 15 women who had PCEA top-ups had no fall in blood pressure in the standing and sitting positions, though the average blood pressure fell significantly when a top-up was given in the lying position. Maternal heart rate increased significantly at 12 min post top-up when the women were in the standing position (P = 0.0018). In the 15 women who had PCEA top-ups, the CTG showed improvement in decelerations when women were in the standing position but deterioration when in the lying position (P < 0.01).

CONCLUSION

Patient-controlled epidural analgesia top-ups with maternal mobility may be beneficial to the fetus possibly by reducing the hypotension normally associated with top-ups in the lying position.

Aiolos, a lymphoid restricted transcription factor that interacts with Ikaros to regulate lymphocyte differentiation

Development of the lymphoid system is dependent on the activity of zinc finger transcription factors encoded by the Ikaros gene. Differences between the phenotypes resulting from a dominant-negative and a null mutation in this gene suggest that Ikaros proteins act in concert with another factor with which they form heterodimers. Here we report the cloning of Aiolos, a gene which encodes an Ikaros homologue that heterodimerizes with Ikaros proteins. In contrast to Ikaros--which is expressed from the pluripotent stem cell to the mature lymphocyte--Aiolos is first detected in more committed progenitors with a lymphoid potential and is strongly up-regulated as these differentiate into pre-T and pre-B cell precursors. The expression patterns of Aiolos and Ikaros, the relative transcriptional activity of their homo- and heteromeric complexes, and the dominant interfering effect of mutant Ikaros isoforms on Aiolos activity all strongly suggest that Aiolos acts in concert with Ikaros during lymphocyte development. We therefore propose that increasing levels of Ikaros and Aiolos homo- and heteromeric complexes in differentiating lymphocytes are essential for normal progression to a mature and immunocompetent state.

Acute pancreatitis complicating a bone marrow harvest

A patient developing acute pancreatitis with pseudocyst formation after an uncomplicated bone marrow harvest is reported. The diagnosis was confirmed by elevated serum amylase and lipase, and by CT scan. We suggest that the pancreatitis may have been precipitated by spasm of the sphincter of Oddi secondary to opiates administered as premedication and for pain relief.

An audit of knee radiographs performed for general practitioners

The Royal College of Radiologists (RCR) has published guidelines concerning indications for imaging investigations. These include plain radiography of the knee, the indications for which are locking or signs of restricted movement. This audit consisted of 1153 knee radiographs in a 9 month period, results of a questionnaire sent to general practitioners (GPs), analysis of radiological reports and returned questionnaires (55% of cases), and subsequent comments from the GPs on receiving these results. Only 50% of cases fall within RCR guidelines, 90% of radiographs were normal or showed degenerative change. In 42% of cases, knee radiographs were requested to confirm previously expected degenerative change, and in 30% patient pressure was a significant factor. Most knee radiographs (87%) result in no significant change in management apart from continuation of symptomatic measures. Application of current guidelines, however, would miss some important diagnoses manifest clinically by persistent pain or effusion, for example loose body or Brodie's abscess. In cases of locking, where a radiograph may miss significant soft tissue abnormality, there was concern that reassurance was often gained by a normal examination. This audit shows that many knee radiographs are unnecessary. The guidelines appear appropriate with the proviso that persistent pain and effusion should be included as indications for investigation. Many GPs report medico-legal considerations as important reasons for unnecessary referrals, although the application of guidelines should be protection against this. The referral rate for knee radiographs before and after the communication of these results has not altered.

Somatostatin receptor subtype specificity in human fetal pituitary cultures. Differential role of SSTR2 and SSTR5 for growth hormone, thyroid-stimulating hormone, and prolactin regulation

Somatostatin (SRIF), a hypothalamic inhibitor of pituitary growth hormone (GH) and thyroid-stimulating hormone (TSH) secretion, binds to five distinct receptor (SSTR) subtypes. We therefore tested SSTR subtype-specific SRIF analogs in primary human fetal pituitary cultures (23-25-wk gestation) to elucidate their role in regulating human pituitary function. Using reverse transcription-PCR, mRNA expression of SSTR2 and SSTR5 were detected in fetal pituitary by 25 wk. SRIF analog affinities were determined by membrane radioligand binding in cells stably expressing the human SSTR forms. GH secretion was suppressed equally (40-60%, P < 0.005) by analogs preferential for either SSTR2 (IC50 for receptor binding affinity, 0.19-0.42 nM) or SSTR5 (IC50, 0.37 nM), and compounds with enhanced affinity for SSTR2 were more potent (EC50 for GH suppression, 0.05-0.09 nM) than Lanreotide (EC50, 2.30 nM) and SRIF (EC50, 0.19 nM). Similarly, analogs with high affinity for SSTR2 or SSTR5 decreased TSH secretion (30-40%, P < 0.005). However, prolactin was effectively inhibited only by compounds preferentially bound to SSTR2 (20-30%, P < 0.05). Luteinizing hormone was modestly decreased (15-20%) by SSTR2- or SSTR5-specific analogs. An SSTR5-specific analog also exclusively inhibited GH in acromegalic tumor cells. Thus, SRIF regulation of GH and TSH in primary human fetal pituitary cells is mediated by both SSTR2 and SSTR5, both of which are abundantly expressed by 25 wk. In contrast, suppression of prolactin is mediated mainly by SSTR2. These results indicate that SSTR5 is critical for physiologic regulation of GH and TSH. SRIF analogs with selective affinity for this receptor may therefore be more effective in the treatment of hormone-secreting pituitary adenomas.

Late escape from an immunodominant cytotoxic T-lymphocyte response associated with progression to AIDS

The precise role played by HIV-specific cytotoxic T lymphocytes (CTL) in HIV infection remains controversial. Despite strong CTL responses being generated during the asymptomatic phase, the virus persists and AIDS ultimately develops. It has been argued that the virus is so variable, and the virus turnover so great that escape from CTL recognition would occur continually, but so far there is limited evidence for CTL escape. The opposing argument is that evidence for CTL escape is present but hard to find because multiple anti-HIV immune responses are acting simultaneously during the asymptomatic phase of infection. We describe six donors who make a strong CTL response to an immunodominant HLA-B27-restricted epitope. In the two donors who progressed to AIDS, CTL escape to fixation by the same mutation was observed, but only after 9-12 years of epitope stability. CTL escape may play an important role in the pathogenesis of HIV infection.

Novel, cross-restricted, conserved, and immunodominant cytotoxic T lymphocyte epitopes in slow progressors in HIV type 1 infection

HIV-specific cytotoxic T lymphocytes (CTLs) play an important role in the immune response to HIV infection. Long-term nonprogressors (LTNPs) or slow progressors (SPs) in HIV infection may make qualitatively different CTL responses compared to those generated by seropositive individuals who progress to disease at a faster rate. The class I molecule HLA-B*57 has been identified as one restriction element overrepresented in SP groups studied, and, together with the closely related molecule HLA-B*58, occurs commonly in ethnic groups where HIV is most prevalent. In this study, we have identified five new HLA-B*57-restricted CTL epitopes recognized by SP donors, one of which is also HLA-B*5801 restricted. These HLA-B*57-restricted responses represent the dominant HIV-specific CTL response in each of the SP donors tested. These and other such epitopes may be an important component in future vaccine design.

Snoring as part of a dose-response relationship between sleep-disordered breathing and blood pressure

This report addresses the hypothesis that snoring without significant apneas and hypopneas (simple snoring) is associated with elevated blood pressure and cardiovascular disease (CVD). Data on blood pressure, previously diagnosed cardiovascular disease, and sleep-disordered breathing (SDB) status from a population-based sample of 580 adults was analyzed. Systolic and diastolic blood pressures, adjusted for age, sex, and body mass index, increased stepwise across categories of no SDB, simple snoring, mild, moderate, and more severe SDB (p < 0.05). A similar and significant trend was seen for CVD prevalence. The results provide evidence that simple snoring represents the beginning of the SDB severity spectrum and that simple snoring has a proportionately smaller but, nevertheless, significant, risk for elevated blood pressure and CVD.

Gene expression in the limbless mutant: polarized gene expression in the absence of Shh and an AER

Limb buds in the limbless chick begin to form normally but fail to form an AER and ultimately degenerate. Wnt7a and LMX-1, which are restricted to the dorsal half of a normal limb bud, are expressed throughout the ectoderm and mesenchyme of the mutant buds, respectively. Engrailed-1, normally expressed in ventral limb ectoderm, is not expressed in the limbless bud. This defect precedes the normal period of AER formation and no localized expression of genes normally found in the AER is observed in limbless buds. Consistent with the lack of molecular specialization of an AER, Shh and BMP-2 are not expressed in the ZPA of the mutant bud. Despite the lack of Shh, FGF-4, or BMP-2 expression, the hoxd genes are expressed at low levels in the posterior mesenchyme of the bud. Forced expression of Shh fails to rescue the positive feedback loop between the AER and the ZPA and does not lead to distal outgrowth. However, Shh does maintain the part of the bud formed during pre-AER stages. These results support the importance of the dorsal/ventral boundary in the initiation of AER formation and imply that Shh is not required for the initial activation of polarized hoxd gene expression during limb development.

Hypertrophic osteoarthropathy in staging skeletal scintigraphy for lung cancer

AIM

To assess the prognostic significance of hypertropic osteoarthropathy (HOA) discovered on routine staging bone scintigraphy in patients with lung cancer.

PATIENTS AND METHODS

Between 1989 and 1992 all 99mTc-MDP bone scintigrams performed for the staging of bronchogenic carcinoma were reviewed. HOA was diagnosed by the observation of cortical/periosteal increased uptake in the extremities of the long bones. Follow-up and confirmation of the diagnosis was obtained by hospital computer, histology records, operative records, patient notes and radiological data where available.

RESULTS

164 staging scintigrams for lung cancer were identified. Twenty-eight patients (17%) were observed to have HOA. Patients with and without HOA were well matched for age and sex. There was little difference in the distribution of cell type but the HOA groups has a greater incidence of peripheral tumours. There was no significance in survival between the two groups. Two of three long-term survivors had clinically overt HOA and one presented with arthralgia.

CONCLUSION

HOA is often seen on skeletal scintigraphy for staging of lung cancer and has no prognostic significance. The data also support current teaching that a high index of suspicion for HOA, as a cause of arthralgia may lead to early diagnosis of a potentially resectable lung carcinoma.

Maternal expectations and experiences of labour pain and analgesia: a multicentre study of nulliparous women

Six hospitals with large maternity units in five different European countries were involved in this multicentre study. At least 100 primiparae for each country were examined. All mothers received two standardized interviews, one during the last month of pregnancy, and one 24 h after delivery. Maternal expectations and experiences of pain, pain relief, and satisfaction with analgesia and childbirth were assessed by a 100 mm visual analogue scale (VAS). Almost all mothers were seen regularly by an obstetrician or a midwife during pregnancy, had prepared childbirth classes and received antenatal information on labor analgesia techniques. Differences between the five groups were noted in the level of education and socio-economic status. Maternal expectations of labor pain and the answers to the pre-delivery interview varied significantly between the centers, as did maternal knowledge, expectation and ultimate choice of analgesic technique. Generally speaking the level of maternal satisfaction with analgesia and childbirth experience was high; however, epidural analgesia was more effective than other methods of pain relief (P<0.0001). The most satisfied mothers were those who expected more pain, were satisfied with the analgesia received and had good pain relief after analgesia (P<0.001).

Biliary distensibility during per-operative cholangiography as compared to pre-operative ultrasound: a four year follow-up study

INTRODUCTION

It is well recognized that corrected bile duct diameters, as measured by endoscopic retrograde cholangiography (ERC), are often significantly greater than the corresponding ultrasound measurement. This can be attributed to variation in bile duct distensibility and is particularly noted in post cholecystectomy patients, possibly due to loss of the gall bladder reservoir effect. It has been suggested that increased bile duct distensibility may be related to the post-cholecystectomy syndrome. We have observed a similar discrepancy between ultrasound and per-operative cholangiography (POC). This trial investigates whether the discrepancy between ultrasound and POC measurements has clinical significance.

METHOD

Seventy-five patients with normal pre-operative ultrasound and POC undergoing standard open cholecystectomy (with benzodiazepine pre-medication) in 1990 were identified. After allowance for magnification, maximum biliary diameters were obtained for the proximal extra-hepatic bile duct. Follow-up was obtained in 67 patients from clinical case notes and contact with general practitioners.

RESULTS

Considerable variation of bile duct distensibility was recorded (range 83% to 410%) with 12 cases having POC biliary diameters outside radiological guidelines (12 mm as recorded on the radiograph). This distension is shown to increase with age. After 4 years, 16 patients had recurrent abdominal pain of which nine had undiagnosed right upper quadrant pain. There were no clinical cases of retained stone post-operatively. There was no correlation between POC measured bile duct diameter or distensibility and post-operative or long term problems. This study suggests that the bile duct has a normal variation of distensibility which increases with age and that radiological guidelines, as regards the upper limit for normal POC biliary diameters can be relaxed.

The correlation of bone scintigraphy and histological findings in patellar tendinitis

Patellar tendinitis is a chronic overuse injury causing pain and tenderness over the proximal insertion of the patellar tendon. Its management is usually conservative, but in intractable cases surgery is effective. Bone scintigraphy has been suggested as a useful investigation in these patients, although we are aware of no large series supporting this. Thirty-four patients with intractable symptoms of patellar tendinitis were treated surgically. The operative specimens were graded histologically and compared with preoperative radionuclide bone scans. The histological findings confirmed tendon and or tendon sheath abnormalities in all the samples. The predominant abnormalities were increased vascularity, fibroblast proliferation, acid mucopolysaccharide and haemosiderin deposition. Bone scintigraphy showed 24 (71%) patients to have abnormalities on the delayed images, 8 with diffusely increased activity in the patella and 16 with increased activity localized to the lower pole. Patients with abnormal bone scans had significantly more severe histological changes in their tendons. These findings support the use of radionuclide bone scans in the pre-operative assessment of patellar tendinitis correlating well with histopathological severity of the disease process. The 10 false-negative cases (29%), however, suggest that bone scans are unhelpful in the routine diagnosis and management of this condition.

Influence of soil fumigation and seed tuber treatment on the control of Rhizoctonia solani on potatoes

Five field experiments were conducted in South Australia to determine the effect of soil fumigation (metham sodium) and chemical and biological seed tuber dressing on the severity of Rhizoctonia solani on potato stems and tubers. These experiments indicated that both soil- and tuber-borne inoculum must be considered in any program aimed at controlling R. solani. Tuber treatments of either a 20 min dip in 2% formaldehyde, sprays with pencycuron (0.15 mL a.i./10 kg seed), iprodione (2 mL a.i.110 kg seed) or a spore suspension of lo6 spores/ml of Verticillium biguttatum or a dust with tolclofos methyl (4 g a.i.110 kg seed) were most effective if planted in soil fumigated with 500 L/ha metham sodium or soil with low levels of R. solani. A commercial formulation of Trichoderma harziannum and T. koningii applied as a dust at 1.3 g110 kg seed was in most cases ineffective when treated seed was planted into either fumigated or unfumigated soil. The incidence of progeny tubers with sclerotia varied between sites and ranged from 85% in an unfumigated soil planted with infected tubers to 2% in a fumigated soil planted with pencycuron-treated tubers. Except for 1 experiment where tubers were harvested early, neither seed treatments nor fumigation improved total nor marketable yield.

Using a mixture model to predict the occurrence of diabetic retinopathy

Diabetes mellitus is a common condition which has several serious complications associated with it. In this paper a mixture model, based on one previously used to predict the onset of AIDS, is used to predict the onset of one of these complications, diabetic retinopathy, the major cause of adult blindness in the U.K. This model differs from the previous AIDS model by introducing covariates into the model and using a wider choice of mixture distributions. The fit and distributional assumptions of the model are then discussed for this example. The model is fitted to the data by maximum likelihood. It is important that the training set contains balanced numbers of individuals with and without retinopathy.