cAMP and cGMP in human parotid saliva: relationships to taste and smell dysfunction, gender, and age

A Systematic Review of the Role of Purinergic Signalling Pathway in the Treatment of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global health concern. Three years since its origin, despite the approval of vaccines and specific treatments against this new coronavirus, there are still high rates of infection, hospitalization, and mortality in some countries. COVID-19 is characterised by a high inflammatory state and coagulation disturbances that may be linked to purinergic signalling molecules such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine (ADO), and purinergic receptors (P1 and P2). These nucleotides/nucleosides play important roles in cellular processes, such as immunomodulation, blood clot formation, and vasodilation, which are affected during SARS-CoV-2 infection. Therefore, drugs targeting this purinergic pathway, currently used for other pathologies, are being evaluated in preclinical and clinical trials for COVID-19. In this review, we focus on the potential of these drugs to control the release, degradation, and reuptake of these extracellular nucleotides and nucleosides to treat COVID-19. Drugs targeting the P1 receptors could have therapeutic efficacy due to their capacity to modulate the cytokine storm and the immune response. Those acting in P2X7, which is linked to NLRP3 inflammasome activation, are also valuable candidates as they can reduce the release of pro-inflammatory cytokines. However, according to the available preclinical and clinical data, the most promising medications to be used for COVID-19 treatment are those that modulate platelets behaviour and blood coagulation factors, mainly through the P2Y12 receptor.

Potential pharmacologic treatments for COVID-19 smell and taste loss: A comprehensive review

The acute loss of taste and smell following COVID-19 are hallmark symptoms that affect 20-85% of patients. However, the pathophysiology and potential treatments of COVID-19 smell and taste loss are not fully understood. We searched the literature to review the potential pathologic pathways and treatment options for COVID-19 smell and taste loss. The interaction of novel coronavirus with ACE-2 receptors expressed on sustentacular cells and taste buds results in direct damage to the olfactory and gustatory systems. Also, the invasion of the virus to the olfactory neurons and consequent local inflammation are other proposed mechanisms. Therefore, COVID-19 patients with smell or taste loss may benefit from neuroprotective, anti-inflammatory, or depolarizing agents. Based on the current evidence, phosphodiesterase inhibitors, insulin, and corticosteroids can be promising for the management of COVID-19 smell and taste loss. This review provided crucial information for treating COVID-19-related smell and/or taste loss, urging to perform large clinical trials to find optimum treatment options.

Pathophysiology and possible treatments for olfactory-gustatory disorders in patients affected by COVID-19

SARS-CoV-2 infects host cells mainly through the interaction between the virus's Spike protein and the viral receptors namely Angiotensin-Converting Enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Both are highly expressed in the gastrointestinal tract, in the nasal and bronchial epithelium, as well as in the type II alveolar epithelial cells. The aim of this review is to report the evidences from the scientific literature on the pathophysiology and the available treatments for olfactory-gustatory disorders in patients with COVID-19. The mechanisms involved in these disorders are still unclear and studies on specific therapies are scarce. However, it has been hypothesized that a decrease in the sensitivity of the sensory neurons as well as the co-expression of ACE2 and TMPRSS2 in the alveolar epithelial cells are the main causes of olfactory-gustatory disorders. The possible mechanisms described in the literature for changes in taste perception in patients with COVID-19 include olfactory disorders and a competitive activity of COVID-19 on ACE2 receptors in the taste buds. In addition, SARS-CoV-2 can bind to sialic acid receptors in the taste buds. In general, evidences show that there is no specific treatment for olfactory-taste disorders induced by SARS-CoV-2, even though some treatments have been used and have shown some promising results, such as olfactory training, intranasal application of sodium citrate and vitamin A, as well as systemic use of omega-3 and zinc. Corticosteroids have also been used as a pharmacological approach to treat patients with olfactory dysfunction with some contradictory results. The knowledge of the mechanisms by which SARS-CoV-2 influences the sensory systems and how effective therapies can treat the loss of smell and taste will have important implications on the understanding and clinical management of olfactory-taste disorders.

Association of Salivary Content Alteration and Early Ageusia Symptoms in COVID-19 Infections: A Systematic Review

Coronavirus disease 2019 (COVID 19) is a major threat to the health and prosperity of human life at present. It has resulted in loss of thousands of lives globally and has brought countries to the brink of economic, social, and health collapse. A major issue of this infection is the ease with which it transmits through salivary droplets and its survival for long durations outside the body. Therefore, its early detection is critical in prevention, diagnostic, and management efforts of COVID-19 patients. Loss of taste and smell is one of the early symptoms reported in these patients and the virus is abundantly found in the salivary secretion of the infected symptomatic and asymptomatic patients. Infection and inflammation of salivary glands are common among viral infections, particularly in the early stages, which lead to salivary composition changes. Chemosensory sensation of taste is critically dependent on the salivary flow rate and its inorganic constituents, protein levels, specific 3',5'-cyclic adenosine monophosphate and 3',5'-cyclic guanosine monophosphate levels, ghrelins, pH levels, and enzymes. Therefore, the question arises, "Does COVID-19 infection alter the salivary components and composition leading to early transient symptoms of Ageusia and hypogeusia?" This review shows association of the COVID-19 and Ageusia, in addition to the early viral infection of salivary glands and possible changes in salivary flow and content. Therefore, suggesting a potential association between early ageusia in COVID-19 infection and salivary compositional changes.

Interventions for managing taste disturbances

BACKGROUND

The sense of taste is very much essential to the overall health of an individual. It is a necessary component to enjoy one's food, which in turn provides nutrition to an individual. Any disturbance in taste perception can hamper quality of life in such patients by influencing their appetite, body weight and psychological well-being. Taste disorders have been treated using different modalities of treatment and there is no consensus for the best intervention. Hence this Cochrane Review was undertaken. This is an update of the Cochrane Review first published in November 2014.

OBJECTIVES

To assess the effects of interventions for the management of patients with taste disturbances.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 4 July 2017); the Cochrane Central Register of Controlled Trials (CENTRAL; 2017 Issue 6) in the Cochrane Library (searched 4 July 2017); MEDLINE Ovid (1946 to 4 July 2017); Embase Ovid (1980 to 4 July 2017); CINAHL EBSCO (1937 to 4 July 2017); and AMED Ovid (1985 to 4 July 2017). The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for trials. Abstracts from scientific meetings and conferences were searched on 25 September 2017. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing any pharmacological agent with a control intervention or any non-pharmacological agent with a control intervention. We also included cross-over trials in the review.

DATA COLLECTION AND ANALYSIS

Two pairs of review authors independently, and in duplicate, assessed the quality of trials and extracted data. Wherever possible, we contacted trial authors for additional information. We collected adverse events information from the trials.

MAIN RESULTS

We included 10 trials (581 participants), nine of which we were able to include in the quantitative analyses (566 participants). We assessed three trials (30%) as having a low risk of bias, four trials (40%) at high risk of bias and three trials (30%) as having an unclear risk of bias. We only included studies on taste disorders in this review that were either idiopathic, or resulting from zinc deficiency or chronic renal failure.Of these, nine trials with 544 people compared zinc supplements to placebo for patients with taste disorders. The participants in two trials were children and adolescents with respective mean ages of 10 and 11.2 years and the other seven trials had adult participants. Out of these nine, two trials assessed the patient-reported outcome for improvement in taste acuity using zinc supplements (risk ratio (RR) 1.40, 95% confidence interval (CI) 0.94 to 2.09; 119 participants, very low-quality evidence). We meta-analysed for taste acuity improvement using objective outcome (continuous data) in idiopathic and zinc-deficient taste disorder patients (standardised mean difference (SMD) 0.44, 95% CI 0.23 to 0.65; 366 participants, three trials, very low-quality evidence). We also analysed one cross-over trial separately using the first half of the results for taste detection (mean difference (MD) 2.50, 95% CI 0.93 to 4.07; 14 participants, very low-quality evidence), and taste recognition (MD 3.00, 95% CI 0.66 to 5.34; 14 participants, very low-quality evidence). We meta-analysed taste acuity improvement using objective outcome (dichotomous data) in idiopathic and zinc-deficient taste disorder patients (RR 1.42, 95% 1.09 to 1.84; 292 participants, two trials, very low-quality evidence). Out of the nine trials using zinc supplementation, four reported adverse events like eczema, nausea, abdominal pain, diarrhoea, constipation, decrease in blood iron, increase in blood alkaline phosphatase, and minor increase in blood triglycerides.One trial tested taste discrimination using acupuncture (MD 2.80, 95% CI -1.18 to 6.78; 37 participants, very low-quality evidence). No adverse events were reported in the acupuncture trial.None of the included trials could be included in the meta-analysis for health-related quality of life in taste disorder patients.

AUTHORS' CONCLUSIONS

We found very low-quality evidence that was insufficient to conclude on the role of zinc supplements to improve taste acuity reported by patients and very low-quality evidence that zinc supplements improve taste acuity in patients with zinc deficiency/idiopathic taste disorders. We did not find any evidence to conclude the role of zinc supplements for improving taste discrimination, or any evidence addressing health-related quality of life due to taste disorders.We found very low-quality evidence that is not sufficient to conclude on the role of acupuncture for improving taste discrimination in cases of idiopathic dysgeusia (distortion of taste) and hypogeusia (reduced ability to taste). We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.

Anosmia: Differential diagnosis, evaluation, and management

The ability to scrutinize our surroundings remains heavily dependent on the sense of smell. From the ability to detect dangerous situations such as fires to the recollection of a fond memory triggered by an odor, the advantages of an intact olfactory system cannot be overstated. Outcomes studies have highlighted the profound negative impact of anosmia and parosmia on the overall quality of life. The National Institute on Deafness and Other Communication Disorders estimates that ∼1.4% of the United States population experiences chronic olfactory dysfunction and smell loss. Efforts have focused on improving both the diagnosis of olfactory dysfunction through olfactory testing and improved reporting of treatment outcomes of olfactory training. The purpose of this article was to review the differential diagnosis, workup, and current treatment strategies of anosmia and smell disorders.

Erythrocyte membrane antigen frequencies in patients with Type II congenital smell loss

OBJECTIVE

The objective of this study was to determine whether there are genetic factors associated with Type II congenital smell loss.

STUDY DESIGN

The expression frequencies of 16 erythrocyte antigens among patients with Type II congenital smell loss were determined and compared to those of a large control group.

METHODS

Blood samples were obtained from 99 patients with Type II congenital smell loss. Presence of the erythrocyte surface antigens A, B, M, N, S, s, Fy(a), Fy(b), D, C, c, E, e, K, Jk(a), and Jk(b) was analyzed by blood group serology. Comparisons of expression frequencies of these antigens were made between the patients and a large control group.

RESULTS

Patients tested for the Duffy b antigen (Fy(b) haplotype) exhibited a statistically significant 11% decrease in expression frequency compared to the controls. There were no significant differences between patients and controls in the expression frequencies for all other erythrocyte antigens (A, B, M, N, S, s, Fy(a), D, C, c, E, e, K, Jk(a), or Jk(b)).

CONCLUSIONS

These findings describe the presence of a previously unrevealed genetic tendency among patients with Type II congenital smell loss related to erythrocyte surface antigen expression. The deviation in expression rate of Duffy b suggests a target gene and chromosome region in which future research into this form of congenital smell loss may reveal a more specific genetic basis for Type II congenital smell loss.

Interventions for the management of taste disturbances

BACKGROUND

The sense of taste is very much essential to the overall health of the individual. It is a necessary component to enjoying one's food, which in turn provides nutrition to an individual. Any disturbance in taste perception can hamper the quality of life in such patients by influencing their appetite, body weight and psychological well-being. Taste disorders have been treated using different modalities of treatment and there is no consensus for the best intervention. Hence this Cochrane systematic review was undertaken.

OBJECTIVES

To assess the effects of interventions for the management of patients with taste disturbances.

SEARCH METHODS

We searched the Cochrane Oral Health Group Trials Register (to 5 March 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2014), MEDLINE via OVID (1948 to 5 March 2014), EMBASE via OVID (1980 to 5 March 2014), CINAHL via EBSCO (1980 to 5 March 2014) and AMED via OVID (1985 to 5 March 2014). We also searched the relevant clinical trial registries and conference proceedings from the International Association of Dental Research/American Association of Dental Research (to 5 March 2014), Association for Research in Otolaryngology (to 5 March 2014), the US National Institutes of Health Trials Register (to 5 March 2014), metaRegister of Controlled Trials (mRCT) (to 5 March 2014), World Health Organization's International Clinical Trials Registry Platform (WHO ICTRP) (to 5 March 2014) and International Federation of Pharmaceutical Manufacturers and Associations (IFPMA) Clinical Trials Portal (to 5 March 2014).

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing any pharmacological agent with a control intervention or any non-pharmacological agent with a control intervention. We also included cross-over trials in the review.

DATA COLLECTION AND ANALYSIS

Two authors independently, and in duplicate, assessed the quality of trials and extracted data. Wherever possible, we contacted study authors for additional information. We collected adverse events information from the trials.

MAIN RESULTS

We included nine trials (seven parallel and two cross-over RCTs) with 566 participants. We assessed three trials (33.3%) as having a low risk of bias, four trials (44.5%) at high risk of bias and two trials (22.2%) as having an unclear risk of bias. We only included studies on taste disorders in this review that were either idiopathic, or resulting from zinc deficiency or chronic renal failure.Of these, eight trials with 529 people compared zinc supplements to placebo for patients with taste disorders. The participants in two trials were children and adolescents with respective mean ages of 10 and 11.2 years and the other six trials had adult participants. Out of these eight, two trials assessed the patient reported outcome for improvement in taste acuity using zinc supplements (RR 1.45, 95% CI 1.0 to 2.1; very low quality evidence). We included three trials in the meta-analysis for overall taste improvement (effect size 0.44, 95% CI 0.23 to 0.65; moderate quality evidence). Two other trials described the results as taste acuity improvement and we conducted subgroup analyses due to clinical heterogeneity. One trial described the results as taste recognition improvement for each taste sensation and we analysed this separately. We also analysed one cross-over trial separately using the first half of the results. None of the zinc trials tested taste discrimination. Only one trial tested taste discrimination using acupuncture (effect size 2.80, 95% CI -1.18 to 6.78; low quality evidence).Out of the eight trials using zinc supplementation, four reported adverse events like eczema, nausea, abdominal pain, diarrhoea, constipation, decrease in blood iron, increase in blood alkaline phosphatase, and minor increase in blood triglycerides. No adverse events were reported in the acupuncture trial.None of the included trials could be included in the meta-analysis for health-related quality of life in taste disorder patients.

AUTHORS' CONCLUSIONS

We found very low quality evidence that was insufficient to conclude on the role of zinc supplements to improve taste perception by patients, however we found moderate quality evidence that zinc supplements improve overall taste improvement in patients with zinc deficiency/idiopathic taste disorders. We also found low quality evidence that zinc supplements improve taste acuity in zinc deficient/idiopathic taste disorders and very low quality evidence for taste recognition improvement in children with taste disorders secondary to chronic renal failure. We did not find any evidence to conclude the role of zinc supplements for improving taste discrimination, or any evidence addressing health-related quality of life due to taste disorders.We found low quality evidence that is not sufficient to conclude on the role of acupuncture for improving taste discrimination in cases of idiopathic dysgeusia (distortion of taste) and hypogeusia (reduced ability to taste). We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.

Biologically active substances-enriched diet regulates gonadotrope cell activation pathway in liver of adult and old rats

According to the Hippocrates’ theorem “Let food be your medicine and medicine be your food”, dietary interventions may induce changes in the metabolic and inflammatory state by modulating the expression of important genes involved in the chronic disorders. The aim of the present study was to evaluate the influence of long-term (14 months) use of biologically active substances-enriched diet (BASE-diet) on transcriptomic profile of rats’ liver. The experiment was conducted on 36 Sprague–Dawley rats divided into two experimental groups (fed with control or BASE-diet, both n = 18). Control diet was a semi-synthetic diet formulated according to the nutritional requirements for laboratory animals. The BASE-diet was enriched with a mixture of polyphenolic compounds, β-carotene, probiotics, and n-3 and n-6 polyunsaturated fatty acids. In total, n = 3,017 differentially expressed (DE) genes were identified, including n = 218 DE genes between control and BASE groups after 3 months of feeding and n = 1,262 after 14 months. BASE-diet influenced the expression of genes involved particularly in the gonadotrope cell activation pathway and guanylate cyclase pathway, as well as in mast cell activation, gap junction regulation, melanogenesis and apoptosis. Especially genes involved in regulation of GnRH were strongly affected by BASE-diet. This effect was stronger with the age of animals and the length of diet use. It may suggest a link between the diet, reproductive system function and aging.

Taste and smell function in chronic disease: a review of clinical and biochemical evaluations of taste and smell dysfunction in over 5000 patients at The Taste and Smell Clinic in Washington, DC

PURPOSE

To describe systematic methods developed over 40 years among over 5000 patients at The Taste and Smell Clinic in Washington, DC to evaluate taste and smell dysfunction.

MATERIALS AND METHODS

A tripartite methodology was developed. First, methods to determine clinical pathology underlying the multiple disease processes responsible for taste and smell dysfunction were developed. Second, methods to determine biochemical parameters responsible for these pathologies were developed. Third, methods to implement these techniques were developed to form a unified basis upon which treatment strategies can be developed to treat these patients.

RESULTS

Studies were performed in 5183 patients. Taste loss was present in 62% of patients, smell loss in 87%. Most patients with taste loss (52%) exhibited Type II hypogeusia; most patients with smell loss (56%) exhibited Type II hyposmia. Sensory distortions were present in 60%. Four common diagnostic entities were found: post influenza-type hyposmia and hypogeusia (27% of patients), idiopathic causes (16%), allergic rhinitis (15%) and post head injury (14%). Regardless of clinical diagnosis the major biochemical abnormality found in most patients (~70%) was diminished parotid salivary and nasal mucus secretion of cAMP and cGMP.

CONCLUSIONS

Taste and smell dysfunctions are common clinical problems associated with chronic disease processes. These symptoms require a systematic, integrated approach to understand their multiple and complex components. The approach presented here can and has led to effective treatment.

Possible peripheral mechanism for taste disorder in rats administered S-1

BACKGROUND

Taste disorders are frequently observed in cancer patients undergoing chemotherapy and are serious adverse events which impair the quality of life (QoL) of the cancer patient. Nevertheless, taste disorder mechanisms in cancer patients undergoing chemotherapy have not yet been fully elucidated. The aim of this study was to reveal taste disorder-related peripheral mechanisms using the two-bottle preference test (TBPT) and histological examination of tongues by hematoxylin-eosin staining and immunohistochemistry with protein-gene product 9.5.

METHODS

In the TBPT, one bottle was filled with the 0.01 mM quinine hydrochloride (quinine), as a bitter compound, and the other was filled with water. Doses of 50 and 100 mg kg(-1) day(-1) S-1 (tegafur/gimeracil/oteracil potassium) are lethal to Wistar rats. Therefore, doses ranging from 2-20 mg kg(-1) day(-1) were administered to the rats for 3 weeks. The S-1 dose of 2 mg kg(-1) day(-1) corresponds to the clinical dose administered to cancer patients. The part of the tongue containing the circumvallate papillae was excised the following TBPT.

RESULTS

The rate of increase in terms of the average preference rate for the quinine vs. all intake (quinine plus water) was significant from the initial S-1 period to the final one, compared with that in control rats, suggesting the possibility of a worsening sensation for the bitter taste. In S-1 rats, the area of taste nerve fibers were significantly decreased and the rate of degeneration of intra-tongue ganglionic nerve cells was significantly increased. These changes were significantly correlated with the rate of increase in average preference rate of the quinine.

CONCLUSION

Neuropathy of the gustatory nerve at the periphery may be involved in taste disorders induced by an anticancer drug.

Collection and determination of nucleotide metabolites in neonatal and adult saliva by high performance liquid chromatography with tandem mass spectrometry

Saliva contains a number of biochemical components which may be useful for diagnosis/monitoring of metabolic disorders, and as markers of cancer or heart disease. Saliva collection is attractive as a non-invasive sampling method for infants and elderly patients. We present a method suitable for saliva collection from neonates. We have applied this technique for the determination of salivary nucleotide metabolites. Saliva was collected from 10 healthy neonates using washed cotton swabs, and directly from 10 adults. Two methods for saliva extraction from oral swabs were evaluated. The analytes were then separated using high performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS). The limits of detection for 14 purine/pyrimidine metabolites were variable, ranging from 0.01 to 1.0μM. Recovery of hydrophobic purine/pyrimidine metabolites from cotton tips was consistently high using water/acetonitrile extraction (92.7-111%) compared with water extraction alone. The concentrations of these metabolites were significantly higher in neonatal saliva than in adults. Preliminary ranges for nucleotide metabolites in neonatal and adult saliva are reported. Hypoxanthine and xanthine were grossly raised in neonates (49.3±25.4; 30.9±19.5μM respectively) compared to adults (4.3±3.3; 4.6±4.5μM); nucleosides were also markedly raised in neonates. This study focuses on three essential details: contamination of oral swabs during manufacturing and how to overcome this; weighing swabs to accurately measure small saliva volumes; and methods for extracting saliva metabolites of interest from cotton swabs. A method is described for determining nucleotide metabolites using HPLC with photodiode array or MS/MS. The advantages of utilising saliva are highlighted. Nucleotide metabolites were not simply in equilibrium with plasma, but may be actively secreted into saliva, and this process is more active in neonates than adults.

Etiological relationships of parotid saliva cyclic nucleotides in patients with taste and smell dysfunction

OBJECTIVE

We previously demonstrated that parotid saliva cAMP and cGMP were lower in patients with taste and smell dysfunction than in normal subjects. We subsequently demonstrated parotid saliva cAMP and cGMP were inversely correlated with smell loss degree such that as smell loss severity increased parotid saliva cAMP and cGMP decreased proportionately. To learn more about these relationships we studied parotid saliva cAMP and cGMP with respect to aetiology of sensory loss in these patients.

DESIGN

Parotid saliva cAMP and cGMP in patients with smell loss (hyposmia) who participated in an open label fixed design controlled clinical trial with treatment with oral theophylline were evaluated with respect to their initial etiological diagnosis. Levels of cyclic nucleotides in each etiological category were compared to each other, to the entire patient group and to normal subjects.

RESULTS

Mean cAMP and cGMP in all patients combined were below those in normals, as previously described. However, categorized by aetiology, there was a stratification of levels of both cyclic nucleotides; some levels were below the normal mean and some were at or above the normal mean.

CONCLUSIONS

Parotid saliva cyclic nucleotides characterised in hyposmic patients by aetiology indicate (1) there are differential alterations in these nucleotides related to aetiology of sensory dysfunction and (2) these moieties measured prior to treatment indicate which patient groups may benefit from treatment with phosphodiesterase (PDE) inhibitors which increase levels of these moieties and thereby correct their sensory dysfunction.

Relative resistance to oral theophylline treatment in patients with hyposmia manifested by decreased secretion of nasal mucus cyclic nucleotides

INTRODUCTION

Oral treatment with the phosphodiesterase inhibitor theophylline in an open-label fixed-design clinical trial in 312 patients with hyposmia improved smell function in >50%. Before treatment, all patients had lower than normal levels of nasal mucus cAMP and cGMP. The purpose of this study was to study relationships among changes in smell function, theophylline levels and nasal mucus cAMP and cGMP among patients whose smell function improved (responders) and those who did not improve (nonresponders) on oral theophylline treatment.

METHODS

After all data analysis from the clinical trial was completed, data from each of the 31 of the 312 patients in whom nasal mucus cAMP and cGMP and theophylline levels were available before and after theophylline treatment at several drug doses were evaluated. At initiation and at termination of each treatment, dose smell function, nasal mucus cAMP and cGMP and plasma theophylline were analyzed.

RESULTS

On the same theophylline dose, although serum theophylline increased among both responders and nonresponders, serum levels were consistently higher among responders. Nasal mucus cAMP and cGMP were also higher among responders than nonresponders. At higher theophylline doses, cGMP reached normal levels among responders, whereas it did not change significantly among nonresponders.

CONCLUSIONS

Some patients with hyposmia with initially low nasal mucus cAMP and cGMP levels may be relatively resistant to oral theophylline treatment. This result may offer a mechanism of response lack among some patients whose smell function did not improve after oral theophylline treatment although other factors may influence their response lack.

Improvement in smell and taste dysfunction after repetitive transcranial magnetic stimulation

BACKGROUND

Olfactory and gustatory distortions in the absence of odors or tastants (phantosmia and phantageusia, respectively) with accompanying loss of smell and taste acuity are relatively common symptoms that can occur without other otolaryngologic symptoms. Although treatment of these symptoms has been elusive, repetitive transcranial magnetic stimulation (rTMS) has been suggested as an effective corrective therapy.

OBJECTIVE

The objective of the study was to assess the efficacy of rTMS treatment in patients with phantosmia and phantageusia.

METHODS

Seventeen patients with symptoms of persistent phantosmia and phantageusia with accompanying loss of smell and taste acuity were studied. Before and after treatment, patients were monitored by subjective responses and with psychophysical tests of smell function (olfactometry) and taste function (gustometry). Each patient was treated with rTMS that consisted of 2 sham procedures followed by a real rTMS procedure.

RESULTS

After sham rTMS, no change in measurements of distortions or acuity occurred in any patient; after initial real rTMS, 2 patients received no benefit; but in the other 15, distortions decreased and acuity increased. Two of these 15 exhibited total inhibition of distortions and return of normal sensory acuity that persisted for over 5 years of follow-up. In the other 13, inhibition of distortions and improvement in sensory acuity gradually decreased; but repeated rTMS again inhibited their distortions and improved their acuity. Eighty-eight percent of patients responded to this therapeutic method, although repeated rTMS was necessary to induce these positive changes.

INTERPRETATION

These results suggest that rTMS is a potential future therapeutic option to treat patients with the relatively common problems of persistent phantosmia and phantageusia with accompanying loss of taste and smell acuity. Additional systematic studies are necessary to confirm these results.

Differences between and within human parotid saliva and nasal mucus cAMP and cGMP in normal subjects and in patients with taste and smell dysfunction

BACKGROUND

We previously described some of the moieties in human saliva and nasal mucus including cyclic nucleotides. However, comparison of levels of these latter moieties in saliva and nasal mucus has not been performed and meaning of differences found has not been discussed.

PURPOSE

To compare the levels of cAMP and cGMP in saliva and nasal mucus and to describe the differences in their concentrations and function.

METHODS

cAMP and cGMP in saliva and nasal mucus were compared in normal subjects and patients with taste and smell dysfunction by use of a spectrophotometric colorimetric ELISA.

RESULTS

Both cAMP and cGMP were present in saliva and nasal mucus of normals and patients with levels of both moieties lower in patients than in normals. In normals, cAMP is 6½ times higher in saliva than in nasal mucus whereas cGMP in nasal mucus is 2½ times higher than in saliva. In patients, these differences persist but are less robust. In normals, within saliva, cAMP is 9½ times higher than cGMP whereas within nasal mucus cAMP is half the level of cGMP. In patients, within saliva, these differences persist but at variable differences.

CONCLUSIONS

Both saliva and nasal mucus cAMP and cGMP play roles in taste and smell function, and differences in their concentrations may offer insight into these roles. In nasal mucus, cGMP may be more relevant than cAMP in activity of olfactory epithelial cell function. In saliva, cAMP may be more relevant as a growth factor in taste bud function than cGMP.

Carbonic anhydrase I, II, and VI, blood plasma, erythrocyte and saliva zinc and copper increase after repetitive transcranial magnetic stimulation

INTRODUCTION

Repetitive transcranial magnetic stimulation (rTMS) has been used to treat symptoms from many disorders; biochemical changes occurred with this treatment. Preliminary studies with rTMS in patients with taste and smell dysfunction improved sensory function and increased salivary carbonic anhydrase (CA) VI and erythrocyte CA I, II. To obtain more information about these changes after rTMS, we measured changes in several CA enzymes, proteins, and trace metals in their blood plasma, erythrocytes, and saliva.

METHODS

Ninety-three patients with taste and smell dysfunction were studied before and after rTMS in an open clinical trial. Before and after rTMS, we measured erythrocyte CA I, II and salivary CA VI, zinc and copper in parotid saliva, blood plasma, and erythrocytes, and appearance of novel salivary proteins by using mass spectrometry.

RESULTS

After rTMS, CA I, II and CA VI activity and zinc and copper in saliva, plasma, and erythrocytes increased with significant sensory benefit. Novel salivary proteins were induced at an m/z value of 21.5K with a repetitive pattern at intervals of 5K m/z.

CONCLUSIONS

rTMS induced biochemical changes in specific enzymatic activities, trace metal concentrations, and induction of novel salivary proteins, with sensory improvement in patients with taste and smell dysfunction. Because patients with several neurologic disorders exhibit taste and smell dysfunction, including Parkinson disease, Alzheimer disease, and multiple sclerosis, and because rTMS improved their clinical symptoms, the biochemical changes we observed may be relevant not only in our patients with taste and smell dysfunction but also in patients with neurologic disorders with these sensory abnormalities.

Intranasal insulin: from nose to brain

BACKGROUND

Intranasal insulin has proven useful to control hyperglycemia in diabetics but its mechanism of action has not been well defined. We attempted to understand several aspects of human insulin metabolism by measurement of and interaction of insulin and its associated moieties in nasal mucus, saliva and blood plasma under various physiological and pathological conditions.

METHODS

Insulin, insulin receptors, insulin-like growth factor 1 (IGF1) and insulin-like growth receptor 3 (IGFR3) were measured in nasal mucus, saliva and blood plasma in normal subjects, in thin and obese subjects and in diabetics under fasting and fed conditions.

RESULTS

There are complex relationships among each of these moieties in each biological fluid. Insulin and its associated moieties are present in both nasal mucus and saliva. These moieties in nasal mucus and saliva report on physiological and pathological changes in glucose metabolism as do these moieties in plasma. Indeed, insulin and its associated moieties in nasal mucus may offer specific data on how insulin enters the brain and thereby play essential roles in control of insulin metabolism.

INTERPRETATION

These data support the concept that insulin is synthesized not only in parotid glands but also in nasal serous glands. They also support the concept that insulin enters the brain following intranasal administration either 1) by direct entry through the cribriform plate, along the olfactory nerves and into brain parenchyma, 2) by entry through specific receptors in blood-brain barrier and thereby into the brain or 3) some combination of 1) and 2). Conversely, data also show that insulin introduced directly into the brain is secreted out of brain into the peripheral circulation. Data in this study demonstrate for the first time that insulin and its associated moieties are present not only in saliva but also in nasal mucus. How these complex relationships among nasal mucus, saliva and plasma occur are unclear but results demonstrate these relationships play separate yet interrelated roles in physiology and pathology of human insulin metabolism.

Decreased parotid salivary cyclic nucleotides related to smell loss severity in patients with taste and smell dysfunction

Parotid salivary levels of cyclic adenosine monophosphate (cAMP) have been previously demonstrated to be lower than normal in patients with taste and smell dysfunction. To define these results more fully, we analyzed parotid salivary levels of cAMP and cyclic guanosine monophosphate (cGMP) with respect to severity of smell loss in these patients. Smell loss severity was defined by psychophysical measurements of olfactory function and classified into 4 types from most severe to least severe loss. This resulted in patients exhibiting, in order of loss severity (from greatest to least), anosmia > type I hyposmia > type II hyposmia > type III hyposmia. Parotid saliva cAMP and cGMP were measured independently using a sensitive spectrophotometric 96-plate enzyme-linked immunosorbent assay technique; mean levels were categorized by clinical classification of loss severity. As smell loss severity decreased, salivary cAMP and cGMP levels increased consistently with each stepwise change of clinical loss severity. This is the first demonstration of biochemical changes in saliva associated with a quantitative classification of smell loss. These results reflect a biochemical method to identify and classify patients with smell loss in some respects similar to initial typing of serum lipid levels to assist in risk classification of patients with cardiovascular disease.