Pediatric Subacute Sclerosing Panencephalitis: A Narrative Review on Measles and the Future of Vaccination

Subacute sclerosing panencephalitis is a rare complication due to persistent measles infection, characterized by cognitive and motor deterioration. Because subacute sclerosing panencephalitis is considered a potentially fatal complication of measles and usually presents in young populations, particularly those with measles infection under the age of 2 years, new approaches to implement vaccination programs must be devised to help avoid the worsening of patient outcome. Until the disease is eradicated globally, children in all regions of the world remain at risk of measles infection and its respective complications, and therefore, the vaccine is considered the optimal preventative measure. The legacy of measles virus goes beyond the immediate complications. Our study, therefore, aims to provide a comprehensive review on the updated insights into subacute sclerosing panencephalitis as a complication, as well as the extent and future considerations pertaining to vaccination programs in the pediatric population.

Early Detection of Subclinical Atherosclerosis: Hyperhomocysteinemia as a Promising Marker in Adolescents With Vitamin B Deficiency

In recent decades, the increased incidence of cardiovascular disease (CVD) mortality among young adults has raised concerns. Although clinical manifestations of CVD typically occur later in life, the underlying pathological processes emerge early on. This review article summarizes the association between vitamin B deficiency-induced hyperhomocysteinemia and subclinical atherosclerosis in adolescents. Numerous studies have demonstrated that elevated homocysteine levels are an independent risk factor for endothelial dysfunction (ED) and arterial stiffness, which are key contributors to CVD. Notably, vitamin B deficiency, particularly in vitamin B9 and vitamin B12, emerges as a significant factor in childhood hyperhomocysteinemia, initiating the development of subclinical atherosclerosis in early life. A comprehensive review of relevant literature from prominent bibliographic databases, including PubMed/MEDLINE, PubMed Central, Google Scholar, and Cochrane, was performed. Four cross-sectional studies focusing on homocysteine levels as an exposure variable and markers of atherosclerosis as outcome measures were included and reviewed as part of our analysis. The reviewed studies demonstrate a positive correlation between homocysteine levels and markers of atherosclerosis, including increased carotid intima-media thickness (CIMT) and ED. Mainly, adolescents with vitamin B12 deficiency exhibit a significant positive correlation between homocysteine levels and CIMT. These findings underscore the potential of hyperhomocysteinemia as an early marker for detecting subclinical atherosclerosis in adolescents with vitamin B deficiency. Despite limited research in this area, recognizing the importance of early detection and management of subclinical atherosclerosis in adolescents can help mitigate the risk of severe cardiovascular events such as myocardial infarction and stroke in young adulthood.

Clinical management and humoral immune responses to rabies post-exposure prophylaxis among three patients who received solid organs from a donor with rabies

BACKGROUND

The rabies virus causes a fatal encephalitis and can be transmitted through organ transplantation. In 2013, a man developed rabies 18 months after receiving a kidney from a donor with rabies, who was not known to have been infected when the organs were procured. Three additional persons who received organs from the same donor (liver, kidney, heart), all of whom were not vaccinated for rabies before transplantation, received rabies post-exposure prophylaxis (PEP) with rabies immune globulin and 5 doses of rabies vaccine as soon as the diagnosis of rabies was made in the donor (18 months after their transplant surgeries). We describe their clinical management.

METHODS

As the 3 recipients were all on immunosuppressive medications, post-vaccination serologic testing was performed using the rapid fluorescent focus inhibition test to measure rabies virus neutralizing antibodies (RVNAs). An acceptable antibody response to administration of rabies vaccine was defined as detection of RVNAs at a concentration ≥0.1 IU/mL from a serum specimen collected ≥7 days after the fifth vaccine dose.

RESULTS

All 3 recipients demonstrated an acceptable antibody response despite their immunosuppressed states. More than 36 months have passed since their transplant surgeries, and all 3 recipients have no evidence of rabies.

CONCLUSIONS

The survival of 3 previously unvaccinated recipients of solid organs from a donor with rabies is unexpected. Although the precise factors that led to their survival remain unclear, our data suggest that PEP can possibly enhance transplant safety in settings in which donors are retrospectively diagnosed with rabies.

A large-scale, rapid public health response to rabies in an organ recipient and the previously undiagnosed organ donor

This article describes and contrasts the public health response to two human rabies cases: one organ recipient diagnosed within days of symptom onset and the transplant donor who was diagnosed 18 months post-symptom onset. In response to an organ-transplant-related rabies case diagnosed in 2013, organ donor and recipient investigations were conducted by multiple public health agencies. Persons with potential exposure to infectious patient materials were assessed for rabies virus exposure. An exposure investigation was conducted to determine the source of the organ donor's infection. Over 100 persons from more than 20 agencies spent over 2700 h conducting contact investigations in healthcare, military and community settings. The 564 persons assessed include 417 healthcare workers [5.8% recommended for post-exposure prophylaxis (PEP)], 96 community contacts (15.6% recommended for PEP), 30 autopsy personnel (50% recommended for PEP), and 21 other persons (4.8% recommended for PEP). Donor contacts represented 188 assessed with 20.2% recommended for PEP, compared with 5.6% of 306 recipient contacts recommended for PEP. Human rabies cases result in substantial use of public health and medical resources, especially when diagnosis is delayed. Although rare, clinicians should consider rabies in cases of encephalitis of unexplained aetiology, particularly for cases that may result in organ donation.

Management of the central nasal support complex in naso-orbital ethmoid fractures

Central nasal support structures are frequently injured in patients with naso-orbital ethmoid fractures. Diagnosis of these injuries can be difficult and, to optimally manage them, a thorough understanding of the complex anatomy is essential. The goal of surgical repair is to reestablish the aesthetics and function to this region without complication. Appropriate imaging and classification of the central nasal support injury and classification of the naso-orbital ethmoid fractures must be accomplished prior to formulating a successful treatment plan. This article reviews the anatomy, patient assessment, imaging, and classification systems. Currently accepted management of specific injuries are outlined.

Effect of the parasympathetic system on secretion of parathyroid hormone

This study evaluated the effect of parasympathetic agonists and antagonists on immunoreactive (i) PTH secretion in vitro and on serum iPTH in vivo in rats. In in vitro studies pilocarpine or bethanechol significantly inhibited PTH secretion. This inhibition was blocked by the simultaneous addition of atropine to the incubation medium. In in vivo studies, the cholinergic agonists pilocarpine and bethanechol and the cholinergic antagonist atropine were administered to rats by IV infusion. Blood was obtained before and again after two hours of infusion for analysis of iPTH. Pilocarpine or bethanechol significantly decreased serum iPTH. This inhibition by either agent was blocked by the simultaneous administration of atropine. Administration of atropine alone significantly increased serum iPTH above baseline. This stimulation of basal serum iPTH by parasympathetic blockade suggests that even basal PTH secretion may be influenced by endogenous parasympathetic tone. Therefore, the following conclusions were reached: (1) parasympathetic influences inhibit PTH secretion, and (2) endogenous parasympathetic tone may be an inhibitory modulator of basal secretion of PTH.

Effect of exercise on serum calcium and parathyroid hormone

Previous studies have suggested a role for adrenergic stimuli in the regulation of PTH secretion. In the present studies, we evaluated the effect of endogenous catecholamine stimulation (by treadmill exercise) on serum calcium (Ca) and immunoreactive PTH (iPTH) in six healthy volunteers. Blood was collected for serum total Ca, ionized Ca, iPTH, cAMP, epinephrine, and norepinephrine before, during, and after exercise. As expected, plasma cAMP and catecholamine levels increased significantly during the exercise. In addition, there was an increase in serum total and plasma ionized Ca. However, serum iPTH levels did not change significantly at any of the times tested during and after exercise. The lack of change in serum PTH despite an increase in plasma catecholamines may be explained by 1) an increase in plasma ionized Ca by a separate mechanism (such as metabolic acidosis), which blocked an increase in serum iPTH, or 2) insufficient increase in plasma catecholamines to stimulate PTH secretion.

Parathyroid hormone secretion: effect of beta-adrenergic blockade before and after surgery for primary hyperparathyroidism

Serum immunoreactive parathyroid hormone (iPTH) response to beta-adrenergic blockade by propranolol infusion was determined in 11 normal subjects and 6 patients with primary hyperparathyroidism (PHPT) before and again after the surgical removal of abnormal parathyroid tissue. Propranolol infusion in PHPT patients before surgery resulted in no significant decrease in serum iPTH except at 2 h, when the mean value was 83 +/- 4.4% of baseline. After surgery and achieving a euparathyroid state, the same patients showed a significant propranolol-induced decrease in serum iPTH from baseline at all time periods tested, reaching the nadir value of 57 +/- 7.5% of baseline at 2 h after the start of the propranolol infusion. This response in PHPT patients after surgery was very similar to the response seen in normal subjects. Therefore, this impaired suppressibility of serum iPTH in PHPT is corrected after removal of the abnormal parathyroid tissue. The studies indicate that abnormal parathyroid tissue (either per se or via a metabolic state induced by it) is responsible for the impaired response to beta-adrenergic blockade. It therefore appears unlikely that the impaired beta-adrenergic responsiveness is involved in the pathogenesis of PHPT.

Normal responsiveness of serum parathyroid hormone to beta-adrenergic blockade in patients with secondary hyperparathyroidism

Infusion of calcium gluconate (15 mg Ca++/kg body weight in 4 h) to 6 patients with secondary hyperparathyroidism (due to mild renal insufficiency) decreased serum parathyroid hormone (PTH) levels to the same degree (on a percent basis) as in normal subjects. Serum PTH values at 4 h were 60 +/- 4.5 (SEM)% of baseline in the patients and 59 +/- 2.9% of baseline in the normal subjects. Infusion of propranolol (1 mg i.v. bolus followed by an infusion of 60 micrograms/min for 2 h) to 7 additional patients with secondary hyperparathyroidism also decreased serum PTH to the same degree as in normal subjects. Serum PTH values at 2 h were 68 +/- 10.4% of baseline in the patients and 68 +/- 3.3% of baseline in the normal subjects. The studies indicate normal responsiveness of serum PTH to calcium or beta-adrenergic blockade in secondary hyperparathyroidism due to mild renal insufficiency.

Parathyroid hormone secretion in normal man and in primary hyperparathyroidism: role of histamine H2 receptors

The effect of histamine and histamine H2 receptors on secretion off parathyroid hormone (PTH) was evaluated by 1) adding histamine phosphate (with or without the histamine H2 receptor antagonist, cimetidine) to the medium in in vitro incubation studies with bovine parathyroid tissue, 2) infusing histamine into rats, and 3) infusing the histamine H1 receptor antagonist, diphenhydramine, or cimetidine into normal men and patients with primary hyperparathyroidism. In vitro, histamine (10(-5)-10(-7) M) caused a dose-related significant stimulation of immunoreactive PTH (iPTH) secretion; this was blocked by the simultaneous addition of cimetidine (10(-5) M). Intravenous infusion of histamine significantly increased serum iPTH in rats. In normal man, infusion of diphenhydramine had no effect, but cimetidine (300 or 450 mg) significantly decreased serum iPTH. However, cimetidine had no effect on serum iTh in primary hyperparathyroid patients. The in vitro observations indicate that histamine can stimulate iPTH secretion by a direct effect on the parathyroid cell and that this is probably a specific effect via histamine H2 receptors because the effect was blocked by the H2 receptor antagonist, cimetidine. The observed inhibition of basal PTH concentration by cimetidine induced histamine H2 receptor blockade (but not by H1 blockade) in normal human subjects suggests that endogenous histamine with H2 receptor activation stimulates even basal PTH secretion and may serve as a modulator of PTH secretion in normal man. Loss of this modulating effect of H2 receptors on PTH secretion is a characteristic of primary hyperparathyroidism.

Comparative effect of calcium and of the adrenergic system on calcitonin secretion in man

This study evaluated the effects of adrenergic agents on immunoreactive calcitonin (iCT) secretion in normal man, and compared the time course and magnitude of these adrenergic effects with those caused by modifying calcium (Ca) ion concentration. Ca infusion (15 mg Ca++/kg iv in 4 h) significantly increased plasma iCT within 1 h, reaching 140 +/- 8% of baseline at 4 h. EDTA (50 mg/kg iv in 2 h) significantly decreased plasma iCT within 15 min, with nadir value of 53 +/- 4.9% of baseline at 2 h. The beta-adrenergic agonist, isoproterenol, significantly increased plasma iCT with 5 min, reaching 136 +/- 5.9% of baseline at 30 min. The alpha-adrenergic antagonist, phentolamine, significantly increased iCT within 15 min, reaching 132 +/- 8.6% of baseline at 45 min. The beta-adrenergic antagonist, propranolol, significantly suppressed iCT with 15 min, reaching 51.8 +/-6.3% of baseline at 2 h. Therefore, 1) the adrenergic system (without induced change in serum Ca) can modify CT secretion to as great a degree as can change in Ca ion concentration induced by standard Ca and EDTA infusion tests and 2) even basal secretion of CT can be modified by adrenergic influences. These data strongly suggest 1) that the adrenergic system is an effective modifier of CT secretion and 2) that the adrenergic system, as well as Ca ion concentration, may play an improtant physiological role in control of CT secretion in man.