Concentrations Of Formalin Research Articles

Estimation of Formaldehyde Levels in Indoor Air of Gross Anatomy Laboratory

Introduction: Medical students spend majority of their times in Anatomy lab during their first year MBBS. Formalin has attracted attention as a health hazard for students and instructors as formalin concentrations in air of gross anatomy laboratories are often higher than permissible limits. Despite the known toxicity of formaldehyde and its potential health effects, laboratory workers and others have little enthusiasm for reducing or replacing the formaldehyde working solution Materials and Methods: The FA concentration (in ppm) of indoor air in Anatomy laboratory was measured using a SMILEDRIVE Portable air quality pollution meter. The mean FA concentration was measured after 1 hour after the cadavers were shifted to dissection table at three different levels a. At the level of floor b. At the level of roof c. 2 feets above the table (Breathing Zone of medical students) Three air samples from the breathing zones were tested and mean concentration of FA was taken with exhaust fan on at the level of roof and recorded as a. S1R- First immediately before the dissection (Zero hour), b. S2R- Second sample was collected after one hour after first sample was taken (First hour) and c. S3R- Third sample after two hours after first sample was taken (Second hour). Three air samples from the breathing zones were tested and mean concentration of FA was taken with exhaust fan on at the level of floor and recorded as a. S1F- First immediately before the dissection (Zero hour), b. S2F- Second sample was collected after one hour after first sample was taken (First hour) and c. S3F- Third sample after two hours after first sample was taken (Second hour). Results: The vertical distribution of FA was measured by taking the mean air samples at the level of floor, at roof level and about 2 feet above dissection table immediately after the cadavers were shifted to tables. It was found to be about 0.54ppm at the level of floor, 0.52 at the breathing zone and 0.51 ppm at roof level. The FA concentration was highest at the level of floor and least at the level of roof. On comparing S2F and S2R the p value was 1.335. Thus, it was not statistically significant. On comparing S3F and S3R the p value was 0.411. Thus, it was not statistically significant. Conclusion: The mean FA at the level of floor was 0.54 ppm. At the breathing zone the mean FA concentration was 0.51 ppm before the dissection was started. Exhaust fans at the level of roof were switched on and the second sample was taken after 1 hour. The FA concentration was 0.23 ppm. Third sample was taken at 2nd hour and FA concentration was 0.11 ppm. The exhaust fans at the level of floor were switched on. The air samples were measured at 0, 1st and 2nd hour at breathing zones. It was 0.51, 0.31 and 0,15 ppm respectively.

ELUCIDATING THE EFFECTS OF FORMALIN AS FOOD PRESERVATIVE ON GROSS AND HISTOARCHITECTURE OF VITAL ORGANS OF SWISS ALBINO MICE

Formalin usage as food preservative in Bangladesh has dramatically increased recently, especially in fish, fruits, and many other food products, putting the vast majority of people in serious health risk. With this background, the study was aimed to detect the alterations of gross structure and histoarchitecture of vital organs in Swiss albino mice due to the consumption of formalin. Mice were divided into five groups at the age of four weeks. Normal drinking water was supplied to the control group of mice. Mice of group 1, 2, 3 and 4 were supplied normal drinking water mixed with formalin at 1%, 5%, 10% and 20% concentrations, respectively up to week 24. Mice treated with varying concentrations of formalin for 24 weeks was assessed for the weight change of their liver, heart, kidney and lung weights. Investigations were also conducted on histological alterations in the liver, heart, kidney and lung. After 24 weeks of treatment of mice with different concentrations of formalin, the weight of all four major organs (liver, heart, kidney and lung) was decreased in all formalin-treated mice in comparison to control mice. Petechial hemorrhages, congestion, necrosis, and parenchymatous cell degeneration have been found in liver. Kidney sections have shown decreased Bowman’s space, hypertrophied glomerulus and tubular dilatation. Leucocyte infiltration, necrosis, and rupture of connective tissue have been seen in the heart sections. Lung sections have shown pulmonary alterations, including hemorrhages, thicker alveolar walls, and inflammatory cells. It was, concluded that formalin has adverse effects on vital organs of Swiss Albino mice.

Utilization of Organic Waste as A Natural Detector of Formaldehyde on-Campus Snacks

The aim of this research is to reduce household organic waste through the use of organic waste as a natural detector of formaldehyde content in food snacks. The organic waste used in this study was red garlic skins, dragon fruit skins and purple sweet potato skins. This research is an experimental research. The stages of the research started with the extraction of anthocyanins from the three organic wastes, direct detection of formalin and detection of food ingredients. The formalin concentrations tested were 0.5%, 1%, 2%, 5% and 25%. Detection ability can be seen from the color change between control and formalin treatment. Garlic skin produces a red extract, dragon fruit skin produces an orange extract, and purple sweet potato skin produces a deep red extract. Test results on 20 samples of food snacks around the campus using the three organic waste extracts proved that all samples contained formaldehyde in varying concentrations. The highest 50% formalin content was found in yellow noodles and meatballs. The conclusion is that purple beetle skin, dragonfruit skin, and red garlic skin can be used as natural detectors for formalin in campus snacks.

A Qualitative Analysis of ML Method in Fruits Adultery and Focus on Fruit Adulteration Detection

Detecting formalin can be difficult and time- consuming without exact chemical knowledge. The presence of naturally occurring formalin in food products can additionally make it more difficult to distinguish between formalin that has been purposefully added. The method for dynamic and precise food and formalin identification described in this work is machine learning-based. Preserving food practises that put public nutrition in jeopardy include the unethical use of formalin. It was decided what kind of food to provide based on conductive characteristics. With the use of a VOC HCHO gas sensor and a Renesas, the gadget has the ability of detecting formalin concentrations of 1 to 50 ppm. Polynomial regression has been used in a number of investigations to simulate the application of formalin.

Hematological parameters of Mugil liza mullet submitted to different concentrations of formalin and freshwater

Lebranche mullet, Mugil liza is a species of high economic value for fishing. Despite the importance of the species, little is known about the effects of therapeutic baths on the hematological parameters of mullet. Such parameters are important tools for facilitating the early detection of diseases and illnesses that may impair the performance of the animals. This study evaluated the hematological parameters of mullet submitted to therapeutic baths with formalin and freshwater. For the experiment a total of 108 mullets were used, divided in groups of six individuals per tank. In this experiment, immersion baths were tested for 1 hour in freshwater (zero salinity), formalin at concentrations: 150, 200, 250, 300 and 350 mg L-1 in seawater and a control (without formalin and parasitized), in triplicate. After the immersion bath, fish blood was collected from the caudal vein for evaluation of hematological parameters. The blood was destined to erythrogram, leukogram, thrombogram and glucose determinations. The hematological analyses found significant difference in the number of erythrocytes, lymphocytes, hematocrit, hemoglobin, MCV, MCH, MCHC and glucose. However, there was no significant difference in thrombocyte, total leukocyte, monocyte and neutrophil values. It is concluded that 150 mg L-1 formalin concentration and freshwater bath for one hour can be used for mullet as it causes mild hematological changes.

Investigating the impact of external application of formalin and potassium permanganate on hematological, immunological, and biochemical profiles in Labeo rohita fingerlings

The present study aimed to elucidate the suitability of formalin and KMnO4 as therapeutics for fish diseases in Indian major carp, Labeo rohita, while considering their impact on fish stress levels. Acute toxicity tests revealed that the 96-hour LC50 values for formalin and KMnO4 were 66.58 ppm and 2.89 ppm, respectively. Sub-lethal concentrations of formalin (6.65 ppm, 3.32 ppm, and 2.21 ppm) and KMnO4 (0.289 ppm, 0.145 ppm, and 0.096 ppm), along with control groups, were administered to the fish for different exposure periods (24, 48, 72, and 96 hours) and different hematological, biochemical, and immunological parameters were analyzed. The findings demonstrated that formalin exposure resulted in a significant decrease (p < 0.05) in hematological parameters, immunological parameters, and serum protein levels. Conversely, formalin exposure led to significant increases (p < 0.05) in serum glucose, SGOT, SGPT, and ALP levels. In contrast, KMnO4 exposure significantly decreased (p < 0.05) hematological parameters and serum protein levels, while significantly increasing (p < 0.05) immunological parameters. To evaluate curative efficacy, challenge studies were conducted using three sub-lethal concentrations of formalin and KMnO4 against Aeromonas hydrophila (ATCC 7966) infection. Based on the aforementioned results, the recommended doses of formalin and KMnO4 were found to be 6.65 ppm and 0.289 ppm, respectively.

Concentration, Life Stage, Feeding, Density, Flow, and Strain Effects on Formalin Sensitivity in Rainbow Trout (Oncorhynchus mykiss).

Formalin is one of the most widely used and effective chemotherapeutic compounds for treatment of fungal infections and external parasites of fish eggs and fish. However, exposure to formalin can cause mortality in eggs and fingerlings, dependent upon the concentration used and the rearing conditions in which fish are treated. Additionally, strains within a species can exhibit differential susceptibility to formalin. Four experiments were conducted to evaluate the differential sensitivity to formalin of four rainbow trout (Oncorhynchus mykiss) strains in both the egg and fingerling life stages. Eggs were exposed to concentrations of 1667, 2000, and 5000 ppm formalin, and sensitivity differed among the strains when formalin concentration exceeded 2000 ppm. Exposure to higher formalin concentrations (i.e., 5000 ppm) as eggs did not increase mortality when fish were re-exposed to concentrations of 0, 167, 250, or 500 ppm formalin at 77 mm total length (TL). Fish size affected formalin sensitivity, with larger fish (128 mm TL) exhibiting higher rates of mortality than fish ≤ 77 mm TL when exposed to 250 ppm formalin. The effects of crowding, feeding, flow, and density on the formalin sensitivity of 77 mm TL fish were also investigated. Mortality increased in fish crowded away from the inflow to prevent contact with formalin as it entered the tank, potentially the result of an increase in density index within the crowded tanks. Feeding fish on the day they were treated caused mortality to increase by 5.4 to 8.8% in fish exposed to 167 and 250 ppm formalin, respectively, and mortality differed by strain. Reducing flows by half resulted in doubled to quadrupled mortality, and increased densities resulted in increased mortality in some strains but not others. Hatchery managers should consider what effect rearing conditions and formalin concentrations might have on the strain of fish being treated, prior to large-scale treatment.

Evaluation of Safety and Potency of Kyasanur Forest Disease (KFD) Vaccine Inactivated with Different Concentrations of Formalin and Comparative Evaluation of In Vitro and In Vivo Methods of Virus Titration in KFD Vaccine.

We evaluated the safety and potency of the Kyasanur Forest disease (KFD) vaccine inactivated with different formalin concentrations in mice, since the side effects due to higher formalin concentrations have been a major reason for vaccine refusal. Furthermore, with an objective to reduce the use of mice in vaccine testing, we performed quantification of the KFD virus by real-time PCR and compared it with in vivo titration in mice. The KFD vaccine prepared in chicken embryo fibroblast cells was inactivated with 0.04%, 0.06%, and 0.08% concentrations of formalin. The vaccine inactivated with 0.04% and 0.06% formalin failed the safety test, whereas the KFD vaccine inactivated with 0.08% formalin was safe and potent with a log protective index of 5678 in mice. This reduced formalin content may induce no/lesser side-effects of pain/swelling which may increase the vaccine acceptance. The real-time PCR on individual KFD vaccine harvests interpreted that when the CT value of each harvest is <20, the vaccine will have sufficient viral particles to pass the potency test. Comparison of the real-time PCR on tenfold dilutions of the pooled harvests with in vivo mice inoculation test revealed that the 1MLD50 of the vaccine lies in the tenfold dilution that yields CT values between 31 and 34.

The Impact of Formalin on Postharvest Quality, Shelf Life, and Nutritive Properties of Carrot, Papaya, Plum, Apple Plum, and Guava

As per the news and articles published in mass media in recent years, the usage of formalin in fruits and vegetables has become a worrisome condition in Bangladesh. In this context, this study was conducted to observe the effect of formalin on postharvest quality, shelf life, and nutritional profile of carrot, papaya, plum, apple plum, and guava. Fruits and vegetables sample were treated with different concentrations of formalin solutions (1%, 10%, 20%, and 30%) in two different modes (dipping and spraying) and stored for seven days. Physical parameters (color, texture, and flavor), weight loss, and shelf life were observed on every alternate day during the study period. Furthermore, 20% formalin-treated samples were used to find out the changes in nutritional profile (moisture, ash, carbohydrate, fat, and protein), pH, and vitamin C content. The study results revealed that different concentrations of formalin and treatment methods (dipping and spraying) did not bring up any positive effect in increasing the shelf-life and physical characteristics of selected fruits and vegetables during storage. Moreover, formalin treatment with higher concentration went in faster deterioration in color, texture, and flavor of samples compared to the control. The weight loss of fruits and vegetables is not dependent on formalin application. Formalin treatment worked negatively on the shelf life of samples. A significant reduction (P&lt;0.05) trend on some nutritional parameters (carbohydrate, protein, fat, vitamin C) was observed in formalin-treated apple plum and guava when compared with the control. No significant differences in the pulp pH content were seen as a result of formalin treatment. The overall results suggest that formalin is not a useful preservative to improve the post-harvest qualities and shelf-life of carbohydrate-rich fruits and vegetables at any concentration and mode of application and it has also a negative effect on the nutritional properties of fruits and vegetables.

Histochemical analysis of the biphasic properties of formalin pain-induced behavior

The formalin test has been established as a method for evaluating mouse models of pain. Although there have been numerous reports of formalin-pain-induced behavior, few reports of a detailed histochemical analysis of the central nervous system focus on behavioral biphasic properties.To investigate the alternation of spinal neuronal activity with formalin-induced pain, we performed immunofluorescent staining with c-Fos antibodies as neuronal activity markers using acute pain model mice induced by 2% formalin stimulation. As a result, phase-specific expression patterns were observed. In the spinal dorsal horn region, there were many neural activities in the deep region (layers V−VII) in the behavioral first phase and those in the surface region (layers I−III) in the behavioral second phase. Furthermore, we conducted comparative studies using low concentrations (0.25%) of formalin and capsaicin, which did not show distinct behavioral biphasic properties. Neural activity was observed only in the spinal dorsal horn surface region for both stimuli.Our study suggested that the histochemical biphasic nature of formalin-induced pain was attributable to the activity of the deep region of the spinal cord. In the future, treatment strategies focusing on the deep region neuron will lead to the development of effective treatments for allodynia and intractable chronic pain.

Behavioural Response Detection in Nile Tilapia, Oreochromis niloticus (Linnaeus, 1758) With Different Formalin Concentrations Using Tracker Software-Based Computer Vision Techniques

Changes in fish behaviour caused by stress are difficult to measure. In this study, tracker software-based computer vision techniques were applied, with formalin used as a stressor. At different formalin concentrations, stress responses of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), were examined for fish swimming velocity (FSV) and behaviour. Seven treatments included 1 (control) without formalin, with treatments 2–7 consisting of 100, 200, 300, 400, 500 and 600 mg.L-1formalin concentration, respectively. Three (25 × 51 × 31 cm, width × length × height) glass tanks were 80 % filled with water for each trial. Each tank contained three fish with weights of 0.5–1.0 g, and the FSV of each fish was recorded for 120 min after exposure to formalin. Average FSV statistically differed (P &lt; 0.05) at different formalin concentrations. Treatment 1 (control) gave the highest FSV at 0.038 ± 0.005 m.S-1 followed by treatments 2 (100 mg.L-1) and 3 (200 mg.L-1) at 0.020 ± 0.013 and 0.018 ± 0.020 m.S-1, respectively. Treatments 4 (300 mg.L-1), 5 (400 mg.L-1), 6 (500 mg.L-1) and 7 (600 mg.L-1) recorded 0.007 ± 0.010, 0.006 ± 0.090, 0.004 ± 0.008 and 0.003 ± 0.007 m.S-1, respectively. Differences in FSV at each concentration interval were applied to indicate the behavioural expression of fish response to stress in phase III (tertiary responses). Results indicated that computer vision techniques were suitable for studying Nile tilapia behaviour, with possible applications in other aquatic animals. Highlights of this technique included continuous real-time results to monitor fish stress using a non-invasive method.

Assessment of different formalin concentrations on the histochemical staining of liver, kidneys and lungs of Wistar rats

Assessment of different formalin concentrations on the histochemical staining of liver, kidneys and lungs of Wistar rats

Black Phosphorous-Based Highly Sensitive Surface Plasmonic Sensor for Detection of Formalin

In the present work, a highly sensitive prism-based surface plasmon resonance (SPR) sensor for the detection of formalin using multilayer black phosphorous (BP) is proposed. Formalin, which is widely used as a preservative, can cause a variety of diseases, making its detection crucial. The transfer matrix method is utilized to compare and analyze the proposed structures of the SPR-based prism sensor in the Kretschmann configuration. The effect of prism materials (BAK3, BK7, SF10, SF11, and 2S2G), metals (gold, silver, copper, and aluminum), and 2-D materials (graphene, MoS2, WS2, and BP) on the performance of the sensor for formalin detection has been analyzed and discussed. The analysis of the impact of employing multilayer 2-D materials is carried out. Optimization of the thickness of the 2-D material is performed to achieve a structure that gives better sensitivity. The sensitivity achieved for structures with multilayer graphene, MoS2, and WS2 are 172.82°/RIU, 195.97°/RIU, and 218.04°/RIU, respectively. A highly sensitive structure for formalin detection is proposed with BK7, silver, and nine layers of BP. A sensitivity of 289.4565°/RIU and a detection accuracy (DA) of 0.3125/° are obtained. The limit of detection of the proposed sensor for different concentrations of formalin lies in the range of 3.45– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.56~ \mu $ </tex-math></inline-formula> RIU.

The Development of the Fluorescence-based Portable Device for Lead (II) and Formalin Determination in Food Samples by Using Nitrogen-Doped Carbon Dots (N-CDs).

The fluorescence-based portable device for the determination of lead (Pb2+) and formalin (FA) in food samples by using Nitrogen-doped carbon dots (N-CDs) as a fluorescence probe was developed. The proposed approach, Pb2+, and FA were determined based on the photo-induced electron transfer (PET) mechanism and the silver mirror reaction. The fluorescence intensity of the N-CDs decreased with the increase of Pb2+ concentration and increased with the increasing FA concentration. The fluorescence intensity of N-CDs after the reactions were measured by a filter-free fluorometer platform using a commercial camera module and a Raspberry Pi, a compact computer, as a detector and processor. The experimental results were obtained using control samples with known Pb2+ and FA concentrations in the 0.01-10mg L- 1 and 25-150mg L- 1, respectively. The proposed approach is simple, low-cost, and accurate for the on-site monitoring of Pb2+ and FA in various food samples. Of utmost importance, the proposed approach is expected to be a pioneering model for the future development of other analytes with a broad range of practical applications.

Behaviors associated with formalin-induced pain in the Japanese quail (Coturnix coturnix japonica)

The present study aimed to investigate behaviors associated with formalin-induced nociception in the Japanese quail (Coturnix japonica). The tarsometatarsus region of the male quail's foot (shank) was injected with 40µl of formalin (0.3, 0.6, and 0.9%) solutions or normal saline. Two distinct nociceptive behaviors that is injected foot lifting and flinching/shaking behaviors were recorded over 45 minutes. Also, unstimulated preening, eye closing, and chamber wall pecking behaviors were recorded during the observation period. Subcutaneous injection of formalin 0.6 and 0.9% significantly increased the foot lifting activity in the 0-5 minutes (acute phase) and 15-45 minutes (inflammatory phase) after administration. But the injection of formalin 0.3% significantly increased foot lifting activity only in the acute phase. In the other recorded behaviors, we did not find this biphasic time course pattern. All formalin concentrations induced significant foot flinching/shaking activity only in the acute phase. Subcutaneous injection of formalin 0.9% but not 0.6 and 0.3% significantly increased the duration of eye closure behavior between 20-45 minutes after administration. Injection of all formalin concentrations caused a significant decrease in the unstimulated preening activity between the period of 10 to 45 minutes after administration. Injection of all formalin concentrations caused a significant decrease in the observation chamber wall pecking activity between the period 30 to 45 minutes after administration. These results suggest that the quail formalin test can be considered a relevant, sensitive, and specific technique that helps researchers to use it in the determination of the neurobiology and pharmacology of nociception in the avian species.

Preservation of Goat Kidneys Using Low Concentration Formalin for Human Anatomy Learning

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Exposure to formaldehyde from a preserved cadaver can cause several health problems in students, lecturers, and laboratory technicians working in medical anatomy laboratories. These conditions include respiratory tract irritation and cancer due to acute and chronic exposure, respectively. Lowering the frequency of contact with formaldehyde from preserved organs helps to ensure the safety of students, lecturers, and laboratory technicians. Therefore, this study aims to determine the effectiveness of low concentration formalin as a preservative solution for goat kidneys. The organ was selected due to its anatomical structure similarity to humans.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Method&lt;/strong&gt;: Goat kidneys with 50-60 ml of volume were collected, washed, immersed in preservative solution, and stored for two months. The samples were then divided into four groups, which were preserved with different formalin concentrations, namely 30%, 20%, 10%, and 5%. The preservation parameters, namely organ structure and integrity, color, springiness, odor, and mold growth were qualitatively described, while the kidney volume was quantitatively measured.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results&lt;/strong&gt;: After the samples were preserved for two months, they were observed, and all groups showed similar characteristics. The kidneys preserved with 5% or 10% formalin showed equal volume before and after two months of preservation.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;: Low concentration formalin has the same effectiveness in preserving goat kidneys as the high concentration. It also has the potential to be applied in human anatomy learning.&lt;/p&gt;

Anti-parasitic effects of resveratrol on protoscolices and hydatid cyst layers

The main goal of the current study was to evaluate the effectiveness of resveratrol (RESV) on protoscolices and hydatid cysts of Echinococcus granolosus. Echinococcus granolosus protoscolices and hydatid cyst were exposed to RPMI, DMSO, formalin, mebendazole, and different concentrations of RESV in vitro. Then, viability, GGT, and caspase-3 activity of protoscolices were evaluated using light microscopy, colorimetric, and enzymatic assay, respectively. Tissue changes and expression of caspase-3 apoptosis were analyzed on the hydatid cyst wall by histologic and immunohistochemistry methods. The cell toxicity effect of RESV was evaluated on mouse PBMCs by Annexin V-FITC assay. The RESV-treated protoscolices showed loss of viability, increased gamma-glutamyl transpeptidase, and caspase-3 activity with significant differences compared to all control groups (P < 0.05). Dose and time dependence of mortality, GGT, and caspase-3 enzymatic activity was confirmed in the protoscolices of Echinococcus granulosus treated by RESV. Also, the tissue changes and apoptosis were prominent in RESV-treated hydatid cyst layers; however, tissue changes were only time-dependent, and RESV concentration had no apparent effect on tissue. In cell toxicity evaluation, RESV is safe without any significant apoptosis induction from 31.5 to 250 μg/ml; however, it was significant at 350 and 500 μg/ml in PBMCs.

Effect of morphine and ibuprofen on nociceptive behavior, preening and motor activity following tonic chemical pain in the Japanese quail (Coturnix japonica)

ObjectiveTo establish a tonic chemical model of pain in quail and evaluate the efficacy of opioid and non-steroidal anti-inflammatory drugs. Study designA randomized, blinded, experimental study design. AnimalsA total of 120 male Japanese quail, aged 7 weeks. MethodsA formalin solution (0.3%, 0.6% and 0.9%; total volume of 40 μL) was injected subcutaneously (SC) into the medial aspect of the right metatarsus (shank). Foot lift and preening activities were recorded for 45 minutes following injection of formalin and scored by an investigator blinded to the treatment. An open field test was used to evaluate motor activity. Treatments included SC saline, SC morphine (1.25, 2.5 and 5 mg kg–1) and oral ibuprofen (5 and 10 mg kg–1). The treatment effect was analyzed by one-way anova and the time course effect analyzed using repeated measures anova, both followed by Dunnett’s post hoc test (p < 0.05). ResultsAll formalin concentrations induced significant foot lifting activity in the first phase (0–5 minutes), whereas only 0.6% and 0.9% formalin elicited responses in both the first and second (25–45 minutes) phases. Neither morphine nor ibuprofen affected phase 1 of the formalin test. Morphine (2.5 and 5 mg kg–1) and ibuprofen (5 and 10 mg kg–1) significantly reduced foot lift responses. Preening activity was significantly decreased following injection of 0.6% and 0.9% formalin. Preening was normalized with ibuprofen, but not with morphine. Morphine, but not ibuprofen, reduced quail activity. Conclusion and clinical relevanceThese results suggest that the formalin test was a reliable method for assessing tonic pain behavior in quail. The acute phase of the formalin test was not affected by morphine or ibuprofen. Although ibuprofen reduced the pain response in phase 2, the analgesic effects of morphine were not conclusive because morphine appeared to induce sedation.

The formalin test does not probe inflammatory pain but excitotoxicity in rodent skin.

The most widely used formalin test to screen antinociceptive drug candidates is still apostrophized as targeting inflammatory pain, in spite of strong opposing evidence published. In our rat skin‐nerve preparation ex vivo, recording from all classes of sensory single‐fibers (n = 32), 30 units were transiently excited by formaldehyde concentrations 1–100 mM applied to receptive fields (RFs) for 3 min, C and Aδ‐fibers being more sensitive (1–30 mM) than Aβ−fibers. From 30 mM on, ~1% of the concentration usually injected in vivo, all RFs were defunctionalized and conduction in an isolated sciatic nerve preparation was irreversibly blocked. Thus, formaldehyde, generated a state of ‘anesthesia dolorosa’ in the RFs in so far as after a quiescent interphase all fibers with unmyelinated terminals developed a second phase of vigorous discharge activity which correlated well in time course and magnitude with published pain‐related behaviors. Sural nerve filament recordings in vivo confirmed that higher formalin concentrations (> 42 mM) have to be injected to the skin to induce this second phase of discharge. Patch‐clamp and calcium‐imaging confirmed TRPA1 as the primary transducer of formaldehyde (10 mM) effects on mouse sensory neurons. However, stimulated CGRP release from isolated skin of TRPA1+/+ and TRPA1–/– mice showed a convergence of the saturating concentration‐response curves at 100 mM formaldehyde, which did not occur with nerve and trachea preparations. Finally, skin‐nerve recordings from C and Aδ‐fibers of TRPA1–/– mice revealed a massive reduction in formaldehyde (30 mM)‐evoked discharge. However, the remaining activity was still biphasic, thus confirming additional unspecific excitotoxic actions of the fixative that diffuses along still excitable axons as previously published. The multiplicity of formaldehyde's actions requires extensive discussion and literature review, leading to a fundamental reevaluation of the formalin test.

Immune gene expression and protective effects in goldfish (Carassius auratus L.) immunized with formalin-inactivated cyprinid herpesvirus-2 (CyHV-2) vaccine

The goldfish hematopoietic necrosis viral disease (GHNVD) has led to worldwide economic losses in goldfish aquaculture. The present study has focused on the development of an inactivated vaccine for the cyprinid herpesvirus (CyHV-2) and to check the immunogenicity of the vaccine in the host. The fantail goldfish fin (FtGF) cell line was used in the propagation of the CyHV-2 and the viral titer obtained were of 107.8 TCID50/ml. Followed by the virus was inactivated using 0.1% formalin for 2 days. Various concentrations of formalin-inactivated CyHV-2 (1%, 0.7%, 0.5%, 0.3% and 0.1%) were studied in the FtGF cell line. Morphological changes were observed in the FtGF cell line in all other concentrations of formalin except 0.1% formalin-inactivated CyHV-2 vaccine. The goldfishes were intraperitoneally injected with 300 μl of vaccine and various immune gene responses were studied for a period of 30 days. The gene expression of the adaptive markers CD8, CD4, IFN-ϒ, the cytokines (IL-10, IL-12) was studied in kidney and spleen tissues. Formalin-inactivated CyHV-2 vaccine showed a significant up-regulation of the genes CD8 and IFN-ϒ by the 6th hr post-vaccination onwards. The experimental fish were challenged intraperitoneally with CyHV-2 virus of concentration 107.8 TCID50/ml after 30 days of post-vaccination. A significant difference in cumulative mortality rate was observed for the vaccinated fishes from the unvaccinated fishes. The relative percent survival for formalin immunized fish was 74.03%. Our results have proven that the formalin-inactivated vaccines were efficient and it resulted in triggering the immune gene expression in goldfish. The development and further enhanced studies for this vaccine will lead to a promising low-cost commercial vaccine for CyHV-2 viral infection.