Increased Salt Intake for Orthostatic Intolerance Syndromes: A Systematic Review and Meta-Analysis

BACKGROUND

Guidelines recommend increased salt intake as a first-line recommendation in the management of symptomatic orthostatic hypotension and recurrent syncope. There have been no systematic reviews of this intervention. We sought to summarize the evidence for increased salt intake in patients with orthostatic intolerance syndromes.

METHODS

We conducted a systematic review and meta-analysis of studies in PubMed, EMBASE, and CINAHL. Interventional studies that increased salt intake in individuals with orthostatic intolerance syndromes were included. Primary outcome measures included incidence of falls and injuries, and rates of syncope and presyncope. Secondary outcome measures included other orthostatic intolerance symptoms, blood pressure, and heart rate.

RESULTS

A total of 14 studies were eligible, including participants with orthostatic hypotension, syncope, postural orthostatic tachycardia syndrome, and idiopathic orthostatic tachycardia (n = 391). Mean age was 35.6 (± 15) years. All studies were small and short-term (<60 mins-90 days). No study reported on the effect of increased salt intake on falls or injuries. Meta-analysis demonstrated that during head-up tilt, mean time to presyncope with salt intake increased by 1.57 minutes (95% confidence interval [CI], 1.26-1.88), mean systolic blood pressure increased by 12.27 mm Hg (95% CI, 10.86-13.68), and mean heart rate decreased by -3.97 beats per minute (95% CI, -4.08 to -3.86), compared with control. Increased salt increased supine blood pressure by 1.03 mm Hg (95% CI, 0.81 to 1.25). Increased salt intake resulted in an improvement or resolution of symptoms in 62.3% (95% CI, 51.6 to 72.6) of participants in short-term follow-up studies (mean follow-up of 44.3 days, 6 studies; n=91). Methodological quality of studies were low with high statistical heterogeneity in all meta-analyses.

CONCLUSIONS

Our meta-analysis provides low-quality evidence of a short-term improvement in orthostatic intolerance with increased salt intake. There were no clinical trials demonstrating the efficacy and safety of increased salt intake on long-term clinical outcomes. Overall, there is a paucity of clinical trial evidence to support a cornerstone recommendation in the management of orthostatic intolerance syndromes.

Will vaccination against human papillomavirus prevent eye disease? A review of the evidence

The role of human papillomavirus (HPV) infection in eye disease is controversial. However, a recent case illustrates the possible role of HPV in conjunctival squamous carcinoma and the potentially devastating effects of this disease. The development of two vaccines to prevent infection with HPV types most commonly associated with anogenital cancers has led to debate about the pros and cons of a national immunisation programme to prevent cervical cancer. The introduction of such a vaccination programme may have an additional beneficial effect on the occurrence of some head and neck, including ocular, cancers. This review discusses the nature of papillomaviruses, mechanisms of infection and carcinogenesis, the possible role of HPV in eye disease, and finally the likely impact of the new prophylactic vaccines.

Randomised controlled trial of ketorolac in the management of corneal abrasions

PURPOSE

To evaluate the role of topical non-steroidal anti-inflammatory agents (NSAIDs) in the management of corneal abrasions with respect to symptoms and healing.

METHODS

The study was designed as a prospective, single center, randomised, placebo controlled, double-blinded trial. Eighty-eight consecutive patients with non-infective, non-contact lens related traumatic or foreign body removal related corneal abrasions were recruited to this study. They were randomised into two groups. Both groups were given a single instillation of Gutt. cyclopentolate 0.5% followed by chloramphenicol eye ointment four times a day until the following day. In addition, the treatment group received topical Ketorolac trometamol 0.5% ophthalmic solution while the control group received placebo Liquifilm tears. Patients were assessed at presentation and about twenty-four hours later for subjective symptoms, abrasion size and any associated complications.

RESULTS

There was no statistical difference in the two groups at base line and twenty-four hour follow-up when assessed for five subjective symptoms of pain, photophobia, grittiness, watering and blurring of vision. However, those receiving topical ketorolac required significantly less additional oral analgesics (p=0.001). There was no difference in the rate of healing.

CONCLUSION

Use of topical ketorolac may be a useful adjunct in the management of corneal abrasions.

Complications of phacoemulsification on the first postoperative day: can follow-up be safely changed?

PURPOSE

To establish the rate of complications detected on the first postoperative day and therefore the need for evaluation on that day.

SETTING

Hinchingbrooke Hospital, Huntingdon, England.

METHODS

Complications detected on the first day after phacoemulsification cataract surgery were retrospectively reviewed over 8 months. Ophthalmic nurse practitioners performed the 1 day postoperative examination and kept a log of patients seen, recording complications detected and whether referral to a physician was required. All patients had had routine phacoemulsification with intraocular lens implantation without anterior vitrectomy or trabeculectomy, as identified from the log book and cross-checked with operating theater records. Notes were reviewed if a complication or referral was recorded. Most cases were performed under local anesthesia as day cases using a temporal corneal approach. Sections were routinely left unsutured unless enlarged or closure was not satisfactory at the conclusion of surgery.

RESULTS

The review yielded 392 patients. Six (1.53%) had intraocular pressure (> or = 30 mm Hg) requiring treatment, 1 (0.26%) had painless iris prolapse, 11 (2.81%) had corneal abrasions, and 7 (1.78%) were given a more intensive steroid regime. No cases of fibrinous uveitis were recorded.

CONCLUSIONS

Potentially sight-threatening complications present on the first postoperative day, albeit infrequently. With our current practice and case mix, the need for this review persists. It is possible to reduce the demand on physician time by using appropriately trained nonmedical practitioners.

A histidine protein kinase homolog from the endosymbiont of the hydrothermal vent tubeworm Riftia pachyptila

The uncultivated bacterial endosymbionts of the hydrothermal vent tubeworm Riftia pachyptila play a central role in providing their host with fixed carbon. While this intimate association between host and symbiont indicates tight integration and coordination of function via cellular communication mechanisms, no such systems have been identified. To elucidate potential signal transduction pathways in symbionts that may mediate symbiont-host communication, we cloned and characterized a gene encoding a histidine protein kinase homolog isolated from a symbiont fosmid library. The gene, designated rssA (for Riftia symbiont signal kinase), resembles known sensor kinases and encodes a protein capable of phosphorylating response regulators in Escherichia coli. A second open reading frame, rssB (for Riftia symbiont signal regulator), encodes a protein similar to known response regulators. These results suggest that the symbionts utilize a phosphotransfer signal transduction mechanism to communicate external signals that may mediate recognition of or survival within the host. The specific signals eliciting a response by the signal transduction proteins of the symbiont remain to be elucidated.

Evidence for the presence of a low-level, persistent baculovirus infection of Mamestra brassicae insects

A laboratory culture of Mamestra brassicae insects (MbLC) harbours a latent or occult baculovirus that resembles M. brassicae multiple nucleocapsid nucleopolyhedrovirus (MbMNPV). Although conventional extraction techniques have failed to detect the presence of virus in MbLC, control virus-free insects (MbWS) died of an MbMNPV-like infection after being fed MbLC fat-body cells. This suggested that the MbLC cells harboured infectious MbMNPV, albeit at low levels. We have also demonstrated that fat-body cells from MbLC, but not from MbWS, contain mRNA specific for the polyhedrin gene and transcriptional factors that are capable of activating baculovirus late and very late gene promoters linked to a reporter gene encoding chloramphenicol acetyltransferase. Our data provide indirect evidence that the latent MbMNPV in the MbLC insects is maintained as a persistent infection, with the expression of viral genes at a low level.

Persistent transgene expression in the hypothalamus following stereotaxic delivery of a recombinant adenovirus: suppression of the immune response with cyclosporin

Replication deficient, recombinant adenoviruses (Ads) have been used successfully to transfect several forebrain and brainstem nuclei, but have yet to be demonstrated as useful vectors for transgene delivery in the structurally diverse and highly vascularised nuclei of the hypothalamus. In the present study we have assessed the ability of an Ad expressing the lac-Z gene to transfect cells of the paraventricular nucleus (PVN) of the hypothalamus in vivo. We show that: (1) we can achieve stable expression of the lacZ gene in cells of the magnocellular PVN for at least 2 months; (2) there were no obvious differences in the level of AVP mRNA in the PVNs injected with Ad compared with those injected with vehicle suggesting that Ad treatment is not disrupting normal cellular function in the injection region; (3) the introduction of Ads results in a limited immune response; (4) systemic treatment with cyclosporin dramatically reduces its magnitude. We conclude that Ad vectors represent useful tools for neuroendocrinological and gene therapeutic studies of the hypothalamus.

Superior oblique luxation and trochlear luxation as new concepts in superior oblique muscle weakening surgery

PURPOSE

We used superior oblique luxation and trochlear luxation as new surgical procedures to treat acquired Brown's syndrome and superior oblique muscle overaction.

METHODS

We studied nine patients (11 eyes) who underwent trochlear surgery between 1988 and 1993. Four patients had acquired Brown's syndrome and five had superior oblique muscle overaction. In five patients (six eyes) the trochlea was incised to luxate the superior oblique tendon out of the trochlea. In four patients (five eyes) the trochlea was luxated out of its fossa via a periosteal approach without opening the trochlea itself.

RESULTS

The mean follow-up was 18 months (range, nine to 33 months). Postoperatively, eight patients showed subjective and objective improvement. One patient with painful traumatic acquired Brown's syndrome had no objective improvement but obtained relief of pain.

CONCLUSIONS

These new techniques are a successful alternative in the treatment of acquired Brown's syndrome and superior oblique muscle overaction.

Quantification of latent Mamestra brassicae nuclear polyhedrosis virus in M. brassicae insects using a PCR-scintillation proximity assay

A laboratory culture of Mamestra brassicae insects (MbLC) was found to harbour a latent baculovirus infection. The copy number of the occult MbNPV genome in both the MbLC larvae, and in a cell line derived from the fat body of MbLC was determined by the use of a rapid and convenient PCR-scintillation proximity assay (SPA). The SPA system relies on the use of fluomicrospheres (SPA beads) coated with acceptor molecules which are capable of binding radiolabelled ligands in solution. In the assay described, a biotinylated PCR primer is used and [3H]dNTPs are incorporated into the amplified DNA. The SPA beads are coated with streptavidin, and after binding the biotinylated primer, any amplified, radiolabelled DNA will activate the fluor. The amount of amplified DNA from the target sequence can then be directly quantified using a scintillation counter. The number of MbNPV genomes present in a persistently infected M. brassicae cell, as proposed by SPA, suggest between 13 and 20 copies of the viral genome may be present in individual fat body cells.

Phthirus pubis infestation of the eyelids

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Activation and detection of a latent baculovirus resembling Mamestra brassicae nuclear polyhedrosis virus in M. brassicae insects

A laboratory culture of Mamestra brassicae insects (MbLC) has been found to harbor a latent baculovirus infection. The latent virus was activated by feeding the M. brassicae larvae with either the closely related Panolis flammea nuclear polyhedrosis virus (NPV), or the distantly related Autographa californica NPV. Restriction fragment profiles of the activated virus DNA showed that it is very closely related, if not identical, to M. brassicae NPV. Polymerase chain reaction amplification of polyhedrin gene sequences demonstrated that the latent virus was present throughout the life cycle of the insect; eggs, larvae, pupae, and adults. We failed to detect the presence of a latent virus in a second culture of M. brassicae insects, obtained from the environment and only recently adapted to growth in laboratory conditions, and thus these insects acted as an effective negative control in all the PCR and activation experiments. Using PCR analysis of DNA isolated from dissected tissues of fourth instar MbLC larvae, latent virus sequences were only detected in the fat body. Cell lines established from the isolated MbLC fat body tissue were also shown to harbor the latent virus sequences and should prove useful in further studies to elucidate the mechanisms of latency and virus activation.

Dysthyroid eye disease presenting as Brown's syndrome

A case of acquired Brown's syndrome as a presentation of dysthyroid eye disease is described. Involvement of the superior oblique was confirmed on both CT-scan and MRI. A possible causal mechanism is discussed.

Ablation of the fetal mouse spinal cord: the effect on soleus muscle cytoarchitecture

A technique is described whereby it is possible to surgically ablate the lumbosacral spinal cord of a developing mouse fetus without interfering with fetal viability. The lumbosacral spinal cords of 14-day in utero, 129ReJ mice were ablated with a Cooper Nd-YAG laser, and the fetuses, enclosed in their membranes and attached to the uterus by their placentae, were allowed to develop in the abdominal cavity of the dam. The cytoarchitecture and the temporal pattern of organogenesis of aneural soleus muscles were studied in spaced, serial, transverse, ultrathin sections of muscles of 16- and 18-day gestation and newborn (20-day gestation) mice. At the time of surgery, the soleus muscle was a discrete mass consisting of primary myotubes and a pleomorphic population of mononucleated cells. Axon bundles and blood vessels were found at the muscle's periphery, but had not penetrated throughout the muscle mass. The organogenesis of the aneural muscle was remarkably similar to that of the innervated soleus muscle (Ontell et al., Am J Anat 181:267-278, 1988). In the aneural muscle, as in the innervated muscle, significant numbers of secondary myotubes formed all along the lengths of primary myotubes. Moreover, the time course of myotube formation, the dynamics of cluster formation and cluster dispersal, and the ultrastructural appearance of the myotubes mimicked that observed in innervated muscle. The frequency of necrotic myotubes was no greater in the aneural muscle than in the innervated soleus muscle. Myotube maturation was similar in aneural and innervated soleus muscles until 18 days gestation. However, at birth, aneural myotubes appeared to be slightly less mature than innervated myotubes. Thus, the major morphogenic phenomena that characterize the development of the soleus muscle appear to be independent of innervation.

Morphometric analysis of the developing, murine aneural soleus muscle

The pattern of organogenesis of the aneural soleus muscle of the 129ReJ mouse [rendered aneural by laser ablation of the lumbosacral spinal cord at 14 days in utero (during the period of primary myotube formation, but prior to the formation of secondary myotubes)] was evaluated quantitatively with spaced, serial ultrathin sections and computer-assisted morphometric analysis. Aneural muscles from 16- and 18-day gestation and newborn mice were analyzed to determine age-related changes in a number of parameters including: muscles' maximal girths, numbers of myotubes, myotube diameter distributions, and cluster frequency. Data were compared with a similar study of the organogenesis of the normal soleus muscle (Ontell et al: Am J Anat 181:279-288, 1988). Basic patterns of morphogenesis of the soleus muscle were unchanged by spinal cord ablation, and differences in development between the aneural and innervated muscles were quantitative rather than qualitative. At birth, the aneural muscle contained approximately 76% of the myotubes found in the innervated muscle (approximately 840 myotubes in the innervated muscle and approximately 640 in the aneural muscle). Evidence is presented consistent with the hypothesis that primary myotube formation is reduced by approximately 32% in the aneural muscles and that while extensive secondary myotube formation occurs (approximately 78% of the myotube present at birth in these muscles are secondary myotubes), there is a significant reduction in the number of secondary myotubes in aneural muscles. It is suggested that the reduced numbers of secondary myotubes may be related to the reduction in the number of primary myotubes, which are known to act as scaffolds for secondary myotube formation. The time course of secondary myotube formation and of cluster formation and cluster dispersal and the number of cells per cluster are similar in age-matched, innervated and aneural muscles. The absence of innervation has little effect on myotube growth until birth, when comparison of the myotube diameter distributions reveals a slight alteration in myotube diameter distributions of aneural as compared with innervated muscles.

Intra-ocular pressure changes using the laryngeal mask airway and tracheal tube

Intra-ocular pressure was measured before and throughout airway establishment with either the laryngeal mask airway or tracheal tube. Similar measurements were made on removal of either airway and the amount of coughing noted in the first minute after removal. There was a significantly smaller increase in intra-ocular pressure (p less than 0.001) using the laryngeal mask airway, both on placement and removal, than with the tracheal tube. Postoperative coughing was significantly reduced using the laryngeal mask airway (p less than 0.001). There was a significantly greater rise in heart rate using the tracheal tube (p less than 0.01) probably related to an increased cardiovascular response. The laryngeal mask airway is recommended as an alternative to tracheal intubation in routine and emergency intra-ocular surgery.

Delayed ciliochoroidal detachment following intraocular lens implantation

Three patients who had extracapsular cataract extractions with intraocular lens implants developed delayed ciliochoroidal detachments, which responded to systemic steroid therapy. This rare complication may have been due to ciliary sulcus fixation of the implant. The possible mechanism and treatment are discussed.

The Taylor pressure reducer in cataract surgery

A retrospective study was undertaken to determine whether the use of the Taylor pressure reducer during routine intracapsular cataract surgery lowered the incidence of vitreous loss. A significant reduction in the vitreous loss rate was noted. The Taylor pressure reducer is a useful device for the prevention of this complication in the Third World.

Temperature effects on the parasitic phase of Romanomermis culicivorax in Culex pipiens

The developmental period for the parasitic stage of Romanomermis culicivorax in Culex pipiens was determined at constant and fluctuating temperatures. The median developmental times at 15, 18, 20, 27, and 32 C were 27.6, 17.2, 11.5, 7.1, and 5.8 days, respectively. The optimum temperature range for development of the parasitic stage in C. pipiens was 20 to 32 C. The threshold for development was calculated as 10.4 C, and the heat units required for development were 122.2 +/- 3.6 day-degrees. Development at fluctuating temperatures conformed to that predicted by the constant temperature data.