Anosmia in COVID-19 Associated with Injury to the Olfactory Bulbs Evident on MRI

Patients with coronavirus disease 2019 (COVID-19) may have symptoms of anosmia or partial loss of the sense of smell, often accompanied by changes in taste. We report 5 cases (3 with anosmia) of adult patients with COVID-19 in whom injury to the olfactory bulbs was interpreted as microbleeding or abnormal enhancement on MR imaging. The patients had persistent headache (n = 4) or motor deficits (n = 1). This olfactory bulb injury may be the mechanism by which the Severe Acute Respiratory Syndrome coronavirus 2 causes olfactory dysfunction.

Spectrum of Spinal Cord, Spinal Root, and Brain MRI Abnormalities in Congenital Zika Syndrome with and without Arthrogryposis

BACKGROUND AND PURPOSE

Arthrogryposis is among the malformations of congenital Zika syndrome. Similar to the brain, there might exist a spectrum of spinal cord abnormalities. The purpose of this study was to explore and describe in detail the MR imaging features found in the spinal cords, nerve roots, and brains of children with congenital Zika syndrome with and without arthrogryposis.

MATERIALS AND METHODS

Twelve infants with congenital Zika syndrome (4 with arthrogryposis and 8 without) who had undergone brain and spinal cord MR imaging were retrospectively selected. Qualitative and quantitative analyses were performed and compared between groups.

RESULTS

At visual inspection, both groups showed reduced thoracic spinal cord thickness: 75% (6/8) of the group without arthrogryposis and 100% (4/4) of the arthrogryposis group. However, the latter had the entire spinal cord reduced and more severely reduced conus medullaris anterior roots (respectively, P = .002 and .007). Quantitative differences were found for conus medullaris base and cervical and lumbar intumescences diameters (respectively, P = .008, .048, .008), with more prominent reduction in arthrogryposis. Periventricular calcifications were more frequent in infants with arthrogryposis (P = .018).

CONCLUSIONS

Most infants had some degree of spinal cord thickness reduction, predominant in the thoracic segment (without arthrogryposis) or in the entire spinal cord (with arthrogryposis). The conus medullaris anterior roots were reduced in both groups (thinner in arthrogryposis). A prominent anterior median fissure of the spinal cord was absent in infants without arthrogryposis. Brain stem hypoplasia was present in all infants with arthrogryposis, periventricular calcifications, in the majority, and polymicrogyria was absent.

Odorant substances that trigger headaches in migraine patients

OBJECTIVES

Our objective was to determine odorants that trigger migraine attacks and the time of onset of headache after exposure.

METHODS

Migraine or tension-type headache patients, diagnosed according to the criteria of the International Classification of Headache Disorders-II, were interviewed about lifetime prevalence of headaches triggered by odors and time of onset of pain, after exposure of the patient to the odor.

RESULTS

We studied 200 migraine patients and 200 tension-type headache patients. There were odor-triggered headaches after 25.5 ± 1.9 minutes of exposure in 70.0% (140/200) of migraine patients and none with tension-type headache, which ran at low sensitivity (70.0%, 95% CI 63.1-76.2) and high specificity (100.0%, 95% CI 97.6-100.0). Odor-triggered headaches are distributed in the following order of frequency: perfumes (106/140, 75.7%), paints (59/140, 42.1%), gasoline (40/140, 28.6%) and bleach (38/140, 27.1%). There was significance in the association of odor-triggered migraine, especially among perfume with cleaning (phi = -0.459), cooking (phi = 0.238), beauty products (phi = -0.213) and foul odors (phi = -0.582).

CONCLUSIONS

Odorants, isolated or in association, especially perfume, may trigger migraine attacks after a few minutes of exposure.

A midline sagittal brain view depicted in Da Vinci's "Saint Jerome in the wilderness"

It is estimated that around the year 1480 Leonardo da Vinci painted Saint Jerome in the Wilderness, representing the saint during his years of retreat in the Syrian dessert where he lived the life of a hermit. One may interpret Leonardo's Saint Jerome in the Wilderness as St. Jerome practicing self-chastisement with a stone in his right hand, seemingly punching his chest repeatedly. The stone, the lion and a cardinal's hat are conventionally linked to the saint. A skull was also almost always present with the image of the saint symbolically representing penance. With careful analysis of the painting one can identify the skull which is hidden in an arc represented as a lion's tail. The image is of a hemicranium (midline sagittal view) showing the intracranial dura, including the falx and tentorium, and venous system with the sinuses and major deep veins. This may have been the first time when the intracranial sinuses and the major deep venous vessels were illustrated.

Postdural Puncture Headache is a Risk Factor for New Postdural Puncture Headache

The aim of this study was to determine if patients with a previous history of postdural puncture headache (PDPH) might be prone to a new episode after spinal anaesthesia. Consecutive patients ( n = 258) who had had surgery under spinal anaesthesia were studied. Of 42 patients with a previous history of PDPH, eight (19.0±) developed a new PDPH episode; whereas out of 216 without a previous history of PDPH, only 15 (6.9±) presented with PDPH. Previous PDPH history indicates a higher chance of a new episode of PDPH after spinal anaesthesia. Women are more susceptible to such recurrences.

Immortalized hypothalamic gonadotropin-releasing hormone neurons

The neuroendocrine hypothalamus has been intensively studied using whole animals and tissue slices. However, it has been difficult to approach questions at the molecular and cellular level. By targeting expression of the oncogene product, simian virus 40 T antigen, in transgenic mice using the regulatory domain of the rat gonadotropin-releasing hormone (GnRH) gene, we have produced specific hypothalamic tumours. These tumours have been cultured to produce clonal cell lines (GT-1 cells) that express T antigen, GnRH and many other neuronal markers, but do not express other hypothalamic hormones. These immortal cell lines have a distinctive neuronal phenotype, process the GnRH peptide accurately and secrete GnRH in a pulsatile pattern. Thus, by targeting oncogenesis to a defined population of neurons using the regulatory region of a gene that is expressed late in differentiation of that cell lineage, we have succeeded in immortalizing hypothalamic GnRH neurons. The GT-1 cell lines are an excellent model for future molecular, cell biological, physiological and biochemical investigations into the mechanisms involved in regulation of GnRH and the characteristics of an isolated central nervous system neuron. Their derivation demonstrates the utility of targeting tumorigenesis to specific differentiated neurons of the central nervous system in transgenic mice.

Adenosine A1 receptor-mediated inhibition of in vitro prolactin secretion from the rat anterior pituitary

In previous studies, we demonstrated biphasic purinergic effects on prolactin (PRL) secretion stimulated by an adenosine A2 agonist. In the present study, we investigated the role of the activation of adenosine A1 receptors by (R)-N6-(2-phenylisopropyl)adenosine (R-PIA) at the pituitary level in in vitro PRL secretion. Hemipituitaries (one per cuvette in five replicates) from adult male rats were incubated. Administration of R-PIA (0.001, 0.01, 0.1, 1, and 10 microM) induced a reduction of PRL secretion into the medium in a U-shaped dose-response curve. The maximal reduction was obtained with 0.1 microM R-PIA (mean +/- SEM, 36.01 +/- 5.53 ng/mg tissue weight (t.w.)) treatment compared to control (264.56 +/- 15.46 ng/mg t.w.). R-PIA inhibition (0.01 microM = 141.97 +/- 15.79 vs control = 244.77 +/- 13.79 ng/mg t.w.) of PRL release was blocked by 1 microM cyclopentyltheophylline, a specific A1 receptor antagonist (1 microM = 212.360 +/- 26.560 ng/mg t.w.), whereas cyclopentyltheophylline alone (0.01, 0.1, 1 microM) had no effect. R-PIA (0.001, 0.01, 0.1, 1 microM) produced inhibition of PRL secretion stimulated by both phospholipase C (0.5 IU/mL; 977.44 +/- 76.17 ng/mg t.w.) and dibutyryl cAMP (1 mM; 415.93 +/- 37.66 ng/mg t.w.) with nadir established at the dose of 0.1 microM (225.55 +/- 71.42 and 201.9 +/- 19.08 ng/mg t.w., respectively). Similarly, R-PIA (0.01 microM) decreased (242.00 +/- 24.00 ng/mg t.w.) the PRL secretion stimulated by cholera toxin (0.5 mg/mL; 1050.00 +/- 70.00 ng/mg t.w.). In contrast, R-PIA had no effect (468.00 +/- 34.00 ng/mg t.w.) on PRL secretion stimulation by pertussis toxin (0.5 mg/mL; 430.00 +/- 26.00 ng/mg t.w.). These results suggest that inhibition of PRL secretion after A1 receptor activation by R-PIA is mediated by a Gi protein-dependent mechanism.

Yet another application of the Monte Carlo method for modeling in the field of biomedicine

By means of Monte Carlo simulations performed in the C programming language, an example of scientific programming for the generation of pseudorandom numbers relevant to both teaching and research in the field of biomedicine is presented. The relatively simple algorithm proposed makes possible the statistical analysis of sequences of random numbers. The following three generators of pseudorandom numbers were used: the rand function contained in the stdlib.h library of the C programming language, Marsaglia's generator, and a chaotic function. The statistical properties of the sequences generated were compared, identical parameter values being adopted for this purpose. The properties of two estimators in finite samples of the pseudorandom numbers were also evaluated and, under suitable conditions, both the maximum-likelihood and method of moments proved to be good estimators. The findings demonstrated that the proposed algorithm appears to be suitable for the analysis of data from random experiments, indicating that it has a large variety of possible applications in the clinical practice.

Parkia pendula lectin as histochemistry marker for meningothelial tumour

Lectins have been intensively used in histochemical techniques for cell surface characterization. These proteins are involved in several biological processes and their use as histochemical markers have been evaluated since they can indicate differences in cell surfaces. Parkia pendula lectin (PpeL) was evaluated as histochemical marker for meningothelial meningioma biopsies. Tissue slices were incubated with PpeL conjugated to horseradish peroxidase (PpeL-HRP) and Concanavalin A-HRP (ConA-HPR) and the binding visualized with diaminobenzidine and hydrogen peroxide. The lectin-tissue binding was inhibited with D-glucose. PpeL showed to be a useful tool for the characterization of meningothelial tumour and clinico-pathological diagnosis.

Lateral femoral cutaneous neuralgia: an anatomical insight

A detailed anatomic study was carried out on the lateral femoral cutaneous nerve to better understand the etiology and treatment of lateral femoral cutaneous neuralgia. As it passed from the pelvis into the thigh, the lateral femoral cutaneous nerve ran through an "aponeuroticofascial tunnel," beginning at the iliopubic tract and ending at the inguinal ligament; as it passed through the tunnel, an enlargement in its side-to-side diameter was observed, suggesting that the fascial structures proximal to the inguinal ligament may be implicated in the genesis of lateral femoral cutaneous neuralgia. The finding of pseudoneuromas at this location, distant from the inguinal ligament, supports this hypothesis. The anterior superior iliac spine is located approximately 0.7 cm from the lateral femoral cutaneous nerve and serves as the bony landmark for nerve localization. Within the first 3 cm of leaving the pelvis, the lateral femoral cutaneous nerve was observed deep to the fascia lata; therefore, surgical dissection within the subcutaneous fascia may be conducted with relative impunity near the anterior superior iliac spine just inferior to the inguinal ligament. In 36% of cases there was no posterior branch of the nerve, which is correlated to lateral femoral cutaneous neuralgia symptoms often being limited to the anterior branch region. An accessory nerve was found in 30% of cases.

Nitrergic modulation of vasopressin, oxytocin and atrial natriuretic peptide secretion in response to sodium intake and hypertonic blood volume expansion

The central nervous system plays an important role in the control of renal sodium excretion. We present here a brief review of physiologic regulation of hydromineral balance and discuss recent results from our laboratory that focus on the participation of nitrergic, vasopressinergic, and oxytocinergic systems in the regulation of water and sodium excretion under different salt intake and hypertonic blood volume expansion (BVE) conditions. High sodium intake induced a significant increase in nitric oxide synthase (NOS) activity in the medial basal hypothalamus and neural lobe, while a low sodium diet decreased NOS activity in the neural lobe, suggesting that central NOS is involved in the control of sodium balance. An increase in plasma concentrations in vasopressin (AVP), oxytocin (OT), atrial natriuretic peptide (ANP), and nitrate after hypertonic BVE was also demonstrated. The central inhibition of NOS by L-NAME caused a decrease in plasma AVP and no change in plasma OT or ANP levels after BVE. These data indicate that the increase in AVP release after hypertonic BVE depends on nitric oxide production. In contrast, the pattern of OT secretion was similar to that of ANP secretion, supporting the view that OT is a neuromodulator of ANP secretion during hypertonic BVE. Thus, neurohypophyseal hormones and ANP are secreted under hypertonic BVE in order to correct the changes induced in blood volume and osmolality, and the secretion of AVP in this particular situation depends on NOS activity.

[Idiopathic facial paralysis (Bell's palsy): a study of 180 patients]

The objective of this study was to analyze some clinical and epidemiologic aspects, as well as the follow up of 180 patients with Bell's palsy. In the study population there was a predominance of female (66.7%). Two peaks of incidence in the age distribution were identified: third-fourth and sixth decades of life. In the group of 180 patients there were 198 events of facial paralysis, 17 recurrences and in one patient the paralysis was bilateral at the onset. In 15 patients (8.3%) there were recurrences of the facial paralysis, in 12 cases (70.6%) the recurrences were ipsilateral. The left side of the face was involved in 55.6% of the cases. In eight patients the paralysis occurred during pregnancy (n=5) or puerperium (n=3). As associated conditions we found: arterial hypertension (11.7%), diabetes mellitus (11.1%), pregnancy or puerperium (4.4%; 6.7% in the women), and neurocysticercosis (1.1%). In 72.8% of the cases no association with such conditions was found. In 22.8% of the patients some kind of sequelae were identified: hemifacial spasm (12.8%), partial recovery of the motor deficit (10.6%), syndrome of the crocodile tears (3.3%), sincinetic contraction (2.8%), and the Marcus Gunn inverse phenomenon (1.1%). In conclusion, this study shows that the idiopathic facial paralysis may lead to important sequelae in more than 20% of the patients.

[Etiology of the epileptic seizures in Recife city, Brazil: study of 249 patients]

The etiological causes of the epileptic seizures presenting by 249 patients were studied, in a neurological clinic in Recife City, Brazil. The cause of the seizure was not identified in 43.0% of the patients. As suspected causal factors we found: ischemic cerebrovascular disease (ICVD, 17.3%), cysticercosis (8.8%), head trauma (HT, 6.8%), brain tumors (6.8%), hemorrhagic cerebrovascular disease (HCVD, 4.8%), vascular malformation (3.6%), other causes (8. 4%). In the patients with age less than 15-year-old, the most frequent cause was cysticercosis (10.3%), following vascular malformation (5.1%), and ICVD (5.1%). In the group between 15 and 45 years of age the major cause of seizure was cysticercosis (11.6%), following HT (10.7%), ICVD (4.5%), and brain tumors (3.6%). On the other hand, in the patients with more than 45-year-old the main cause was ICVD (36.7%), following brain tumors (12.3%), HCVD (11.2%), and cysticercosis (5.1%). Im conclusion, cerebrovascular disease was the most prevalent cause of epileptic seizures, considering all groups of patients. Although, cysticercosis was main cause found in the patients with less than 45 years of age.

Experimental murine schistosomiasis and thyroid function

In humans the hepatosplenic form of schistosomiasis may be associated with some degree of somatosexual underdevelopment. In the present study we induced an experimental hepatosplenic form of schistosomiasis by infecting 21-day-old mice with the São Lourenço da Mata-PE strain of Schistosoma mansoni and evaluated thyroid function and its relationship with somatosexual development. Plasma levels of T3 and T4 were determined in 115-day old male albino Swiss mice by radioimmunoassay as a measure of thyroid function. Prepuberal infection with S. mansoni resulted in significant increases in liver (74%) and spleen (138%) weights, although there were no changes in animal growth or plasma T3 and T4 concentrations under the experimental conditions used. The present study demonstrates that prepuberal infection of mice with S. mansoni induces the development of a hepatosplenic form of schistosomiasis during adult life with apparently normal thyroid function.

Inhibitory role of cholinergic agonists on testosterone secretion by purified rat Leydig cells

The effects of cholinometics on basal or hCG-induced testosterone (T) release by Percoll-purified Leydig cells of the rat were studied. Acetylcholine and carbachol as well as nicotine decreased basal and hCG-induced T secretion. The ganglionic nicotine antagonist hexamethonium promoted a partial reversal of the inhibitory effect of nicotine on basal or hCG-stimulated T secretion. Atropine also reduced the inhibitory effect of carbachol on basal or stimulated androgen release. These data indicate that, in short-term incubations, testosterone released by purified Leydig cells is inhibited by nicotinic and muscarinic cholinergic agonists, thus supporting the hypothesis that parasympathetic autonomic system may be involved in the negative regulation of testicular androgen secretion.

Intrinsic pulsatile secretory activity of immortalized luteinizing hormone-releasing hormone-secreting neurons

Mammalian reproduction is dependent upon intermittent delivery of luteinizing hormone-releasing hormone (LHRH) to the anterior pituitary. This mode of secretion is required to sensitize maximally the gonadotrophs to LHRH stimulation and to regulate gonadotropin gene expression. While LHRH secretion is pulsatile in nature, the origin of the pulse generator is unknown. In this report, we show that this oscillator could be located within the LHRH neuronal network. When immortalized LHRH neurons are placed into a perifusion system, LHRH is secreted into the medium in a pulsatile fashion under basal conditions. LHRH secretion and the number of LHRH pulses are reduced when calcium is removed from the medium. Perifusion also influences pro-LHRH processing, since the molar ratio of its processed products varies dramatically when the cells are transferred from a static system. Several different cellular mechanisms may underlie these changes in secretion and processing. Lucifer yellow experiments reveal that some cells are dye-coupled. Hence, these cells could be electrically coupled through gap junctions such that secretion from individual cells could be coordinated. Secretion could also be synchronized through the observed synapse-like contacts. These contacts could perform a negative-feedback role to regulate not only the amount of LHRH released but also the molecular forms secreted. The organization of LHRH neurons into interconnected clusters could serve to coordinate LHRH secretion from individual cells and, thereby, orchestrate functions in vivo as diverse as the onset of puberty, the timing of ovulation, and the duration of lactational infertility.

Role of substance P in the medial preoptic area in the regulation of gonadotropin and prolactin secretion in normal or orchidectomized rats

The present studies were designed to evaluate the role of substance P (SP) in the control of the release of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL). SP was microinjected into the medial preoptic area (MPOA) of conscious, freely moving intact or orchidectomized (ORCX; 21 days post-ORCX) adult male rats. Microinjection of SP into the MPOA induced a significant decrease in plasma LH and FSH concentrations, effects which were accompanied by an elevation in plasma PRL concentration. To examine the participation of endogenously secreted SP in the activity of the MPOA neurons controlling release of these cited pituitary hormones, another study was performed in which either a potent and specific antagonist to SP (D-Pro2, D-Trip7,9-SP; SP-ANT) or an antibody against SP (SP-AB), was injected into the MPOA. SP-ANT and SP-AB both elevated plasma LH, FSH and decreased plasma PRL concentration. These data suggest that endogenous SP within the MPOA exerts an important inhibitory tonus over LH and FSH release and an excitatory tonus over PRL release. In conclusion, SP seems to participate as a neurotransmitter or neuromodulater in the control of LH, FSH and PRL secretion, at least in part, by acting at the level of MPOA, a region in which the neuronal cell bodies that produce LH-releasing hormone and the associated gonadotropin-releasing hormone-associated peptide are located.

Evidence for a negative ultrashort loop feedback mechanism operating on the luteinizing hormone-releasing hormone neuronal system

The present studies were designed to determine whether an ultrashort loop feedback mechanism is involved in the regulation of LHRH secretion. Daily administration of a highly potent LHRH agonist (LHRH-AGO; [D-Ala6,Des-Gly10] LHRH ethylamide) immediately after orchidectomy (ORDX) significantly attenuated the rise of plasma LH from days 2 through 10 after ORDX. Concomitantly with the diminished LH rise after ORDX, a significant increase in LHRH content in the arcuate nucleus was observed in LHRH-AGO-treated rats. Measurement of LHRH levels in hypophyseal portal blood in rats 10 days after ORDX combined with daily agonist treatment revealed a significant decrease in LHRH values in portal plasma compared with those in orchidectomized controls. Arcuate nuclei-median eminence (ME) fragments obtained from ORDX rats treated in vivo with LHRH-AGO for 5 days showed a decreased basal secretion of LHRH and a diminished response to K+ stimulation compared with the release from fragments obtained from ORDX saline-treated controls. To evaluate whether a tonic LHRH inhibitory activity operates within the ME, additional experiments were performed in which ME fragments were incubated in vitro in the presence of a potent LHRH antagonist [( D-pGlu1,D-Phe2,D-Trp3,6]LHRH). The antagonist significantly enhanced the basal secretion of LHRH in a dose-dependent manner. The latter results suggest that LHRH antagonists may enhance LHRH release, perhaps by interacting with LHRH receptors playing an inhibitory role on the endogenous secretion of the decapeptide. These observations strongly suggest a tonic inhibitory or modulatory role of LHRH neurons in the regulation of their own function.