Phytochemical screening and antimicrobial activity of Polygala sadebeckiana Gürke extracts on bacterial isolates from Wound samples of patients with "Shimetere"

BACKGROUND

Modern medicine is not the choice of patients with "shimetere" in the Gurage community owing to their perception of 'parenteral medication use severely aggravates the disease'. For this reason, the root part of Polygala sadebeckiana Gürke is commonly utilized as traditional medicine in the management of the disease. The aim of this study was to evaluate the antimicrobial activity of Polygala sadebeckiana Gürke extract on bacterial isolates from wound samples of patients with "Shimetere".

METHODS

The agar well diffusion method was used to evaluate antibacterial activity, and the agar dilution method was utilized to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MICs). The crude extract was tested against isolated bacteria at concentrations of 25, 50, 75 and 100 mg/mL in triplicate (3x). The positive controls were azithromycin (15 µg) and cloxacillin disk (5 µg), and the negative control was dimethylsulfoxide (5%). The group mean comparisons were made using one-way ANOVA at a significance level of p < 0.05, and the results are presented as the mean ± standard deviation. The presence of secondary metabolites from crude extract was checked by standard testing procedures.

RESULTS

S. aureus and S. pyrogen were the two identified bacteria from 9 (60%) and 3 (20%) wound samples, respectively. All identified bacterial strains were susceptible to the reference antibiotics. Tannins and saponins were the most abundant secondary metabolites found in the crude extracts. The average inhibition zones of the plant extracts with 100, 75, 50 and 25 mg/mL concentrations were 27, 20.33, 15.25, and 11.96 mm (p < 0.000) for S. aureus and 30.02, 24.50, 19.07, and 15.77 mm (p < 0.000) for S. pyrogen bacteria, respectively. The MIC and MBC of the crude extract were 1.67 and 10 mg/mL for S. aureus and 0.98 and 4 mg/mL for S. pyrogen.

CONCLUSION

Polygala sadebeckiana Gürke contained significant tannins and saponins as secondary metabolites and had antibacterial activities against isolated bacteria (S. aureus and S. pyrogen) from "Shimetere". The potential mechanism of antibacterial action of the plant extract was cell wall synthesis inhibition.

Levels of Cytokines in Leptospirosis Patients with Different Serovars and rfb Locus

Leptospirosis has a wide spectrum of clinical manifestations ranging from mild to severe disease. The cytokine response is considered one of the key drivers for this varying manifestation. The different cytokine response observed in patients with leptospirosis could be due to the variation of infecting serovars. Since the rfb locus codes for the lipopolysaccharide synthesis of the bacterial cell wall, which also determines the serovar, this locus may play a role in driving a specific cytokine response in the host. We investigated 12 commonly used cytokine profiles in serum samples of culture, microscopic agglutination test (MAT), or polymerase chain reaction (PCR)-positive patients with leptospirosis. The sequences of the rfb locus in culture-positive samples were generated from whole genome sequencing and serovar status was drawn from original data published. Isolated cultures were subjected to whole genome sequencing using the PacBio RS II system, and the resulting data were used to determine the species. The recovered genomic data were annotated with the Rapid Annotation using Subsystem Technology (RAST) subsystem, and the rfb locus was extracted. The cytokine analysis was carried out using the Qiagen human ELISA kit. Eighteen samples were found to be positive by culture, while the other 7 samples were positive by PCR or MAT. Infections from Leptospira interrogans serovar Autumnalis (5), Pyrogens (3), Icterohaemorrhagiae (1) Leptospira borgpetersenii (all 7 samples clustered in same clonal group with serovar status not determined), Leptospira weilii (1 with serovar status not determined), and Leptospira kirschneri serovar Grippotyphosa (1) were included in the analysis. Three patients [infected with Leptospira interrogansserovar Autumnalis (2) and Pyrogens (1)] and 2 MAT-positive patients (highest titer against serovar Bratislava of L.interrognas) were reported to have severe clinical manifestations, while the rest had mild to moderate symptoms. Although the serum cytokine concentration of patients with severe clinical manifestation was comparatively higher, a statistically significant difference was observed only for interleukin (IL)-1β (P < 0.05). IL-10/tumor necrosis factor-alpha (TNF-α) ratio was high in patients with severe complications. In general, patients infected with L. interrogans showed higher concentration of cytokines compared to L. borgpetersenii.

Using PBMCs in a Multiplex FluoroSpot Assay for Detection of Innate Immune Response-Modulating Impurities (IIRMIs)

The ELISA-based monocyte activation test (MAT) facilitates the replacement of the rabbit pyrogen test (RPT) for the detection of Innate Immune Response-Modulating Impurities (IIRMIs) in injectable drugs by activation of monocytes in human peripheral blood mononuclear cells (PBMCs). We describe the use of a triple-color IL-1β/IL-6/TNF-α FluoroSpot assay as a sensitive tool for quantification of the frequencies of IIRMI-activated monocytes as well as determination of the relative amount of pyrogenic cytokine(s) produced by each activated cell.

Barriers to the Use of Recombinant Bacterial Endotoxins Test Methods in Parenteral Drug, Vaccine and Device Safety Testing

The Bacterial Endotoxins Test (BET) is a critical safety test that is used to detect bacterial endotoxins, which are the major contributor to fever-inducing contamination risks known as pyrogens. All parenteral therapies, including every lot of injected drugs, vaccines, medical devices, must be tested for pyrogens to ensure patient safety. Bacterial endotoxins test methods were developed as a highly sensitive detection method for bacterial endotoxins, after the discovery of a clotting cascade in horseshoe crab blood. However, horseshoe crab species are limited to some inshore coastal habitats along the Atlantic coast of the USA and others throughout Asia. Fully functional horseshoe crab clotting factors can be manufactured via recombinant protein production, and several BET methods featuring recombinant horseshoe crab proteins have now been developed for commercial use. Recombinant Bacterial Endotoxins Test (rBET) methods based on the use of recombinant Factor C (rFC) were established in the European Pharmacopoeia - however, these methods have not yet been granted compendial status in the United States Pharmacopoeia (USP). In order to facilitate dialogue between stakeholders, the Physicians Committee for Responsible Medicine hosted two virtual roundtable discussions on the perceived barriers to the use of rBET methods for US FDA requirements. Stakeholders agreed that multiple rFC-based methods have been demonstrated to have suitable analytical performance, as described in ICH Q2 on the Validation of Analytical Procedures and USP <1225> on the Validation of Compendial Procedures. United States Pharmacopoeia compendial inclusion of the rFC-based and other rBET methods was favoured, in order to reduce the additional burdens created by a lack of global harmonisation on BET testing requirements.

The future of pyrogenicity testing: Phasing out the rabbit pyrogen test. A meeting report

The rabbit pyrogen test (RPT) was the benchmark for pyrogenicity testing, but scientific advancements have provided innovative and humane methods, such as the in vitro monocyte-activation test (MAT). However, transitioning from the RPT to the MAT has been challenging. The European Directorate for the Quality of Medicines & HealthCare, the Council of Europe, and the European Partnership for Alternative Approaches to Animal Testing jointly hosted an international conference entitled "The future of pyrogenicity testing: phasing out the rabbit pyrogen test". The conference aimed to show how the European Pharmacopoeia intends to remove the RPT from its texts by 2026, facilitate the use of MAT, and identify gaps in the suppression of RPT. The events contributed to a better understanding of the barriers to RPT replacement and acceptance of in vitro alternatives. Participants comprised stakeholders from Asia, Europe, and North America, including vaccine developers, contract laboratories, and regulators. Participants shared their replacement strategies and experiences with MAT implementation. They emphasised the need for continued cooperation between stakeholders and stressed the importance of international harmonisation of regulatory requirements to help accelerate MAT acceptance outside Europe. Despite the challenges, the willingness to eliminate the unnecessary use of RPT was common across all participants.

In vitro alternative for reactogenicity assessment of outer membrane vesicle based vaccines

Intrinsic or added immune activating molecules are key for most vaccines to provide desired immunity profiles but may increase systemic reactogenicity. Regulatory agencies require rabbit pyrogen testing (RPT) for demonstration of vaccine reactogenicity. Recently, the monocyte activation test (MAT) gained popularity as in vitro alternative, yet this assay was primarily designed to test pyrogen-free products. The aim was to adjust the MAT to enable testing of pyrogen containing vaccines in an early stage of development where no reference batch is yet available. The MAT and RPT were compared for assessing unknown safety profiles of pertussis outer membrane vesicle (OMV) vaccine candidates to those of Bexsero as surrogate reference vaccine. Pertussis OMVs with wild-type LPS predominantly activated TLR2 and TLR4 and were more reactogenic than Bexsero. However, this reactogenicity profile for pertussis OMVs could be equalized or drastically reduced compared to Bexsero or a whole-cell pertussis vaccine, respectively by dose changing, modifying the LPS, intranasal administration, or a combination of these. Importantly, except for LPS modified products, reactogenicity profiles obtained with the RPT and MAT were comparable. Overall, we demonstrated that this pertussis OMV vaccine candidate has an acceptable safety profile. Furthermore, the MAT proved its applicability to assess reactogenicity levels of pyrogen containing vaccines at multiple stages of vaccine development and could eventually replace rabbit pyrogen testing.

Validation of the monocyte activation test with three therapeutic monoclonal antibodies

Pharmaceutical products intended for parenteral use must be free from pyrogenic (fever-inducing) contamination. Pyrogens comprise endotoxins from Gram-negative bacteria and non-endotoxin pyrogens from Gram-positive bacteria, viruses, and fungi. The longstanding compendial test for pyrogens is the rabbit pyrogen test, but in 2010 the monocyte acti-vation test (MAT) for pyrogenic and pro-inflammatory contaminants was introduced into the European Pharmacopoeia (Ph. Eur.) as a non-animal replacement for the rabbit pyrogen test. The present study describes the first product-specific Good Manufacturing Practice validation of Ph. Eur. MAT, Quantitative Test, Method A for the testing of three therapeutic monoclonal antibodies. The study used the MAT version with cryo-preserved peripheral blood mononuclear cells and interleukin-6 as the readout. Much of the data presented here for one of the antibodies was included in a successful product license application to the European Medicines Agency.

Sterile Basics of Compounding: Methods of Sterilization and Depyrogenation

Many pharmaceutical products are injected into the body or applied to compromised areas. If a product containing microorganisms is introduced into or applied to the body, severe infections may result. Such infections could result in the loss of an organ (e.g., an eye) or a limb, or even result in death. Consequently, certain pharmaceutical preparations must be sterile and contain preservatives to maintain their sterility. Parenteral medications must also be free of pyrogens and have endotoxin levels within allowable limits.

Endotoxins from a Pharmacopoeial Point of View

A pyrogen is a substance that causes fever after intravenous administration or inhalation. Gram negative endotoxins are the most important pyrogens to pharmaceutical laboratories. In the International, United States, Japanese and European Pharmacopoeias, there are two official methods to evaluate pyrogenicitythat is, the bacterial endotoxin test, and the pyrogen test. The main objective of this review is to compare the monographs of each test among the different Pharmacopeias, to detect similarities and differences. The former can be considered fully harmonized, and only non-significant differences were detected. The latter, which is the only available assay for some products and formulations to demonstrate apyrogenicity, shows large differences, which should be considered.

Endotoxin Contamination of Foley Catheters Associated With Fevers Following Transurethral Resection of the Prostate

In 1980 an investigation was conducted due to an apparent cluster of fevers following transurethral resections of the prostate (TURP), where the presence of prostatitis or urinary tract infections (UTIs) could not account for most cases, and the usage of antimicrobials did not prevent them. When unused, prepackaged, sterilized samples from 13 lots of triple lumen catheters were analyzed, four were found to contain high levels of endotoxin (ET), with a range of 49,150-≥ 6.25 ng/catheter. Additionally, these lots were highly pyrogenic to rabbits. The maximum incidence of febrile patients (42%) correlated with usage of catheters from the lot where ET levels were the highest. The febrile rate for a second urologist, who used single lumen catheters, was less (12/33 v 0/12). Further consideration should be given to sterile operative equipment which may still be pyrogenic.

An Examination of Pyrogen from Various Sources

Three distinct types of fever curves can be stimulated by injection of modifications of the same bacterial culture. Injection of a sterilised whole culture causes a double-peak fever:*** the cell-free filtrate or supernatant liquid of a culture stimulates a single-peak fever, rising to a peak in an average time of 86 minutes if the cells are removed before autoclaving, and a double-peak reaction if the culture is autoclaved before removal of the cells; the fever caused by injection of a suspension of washed bacterial cells is a single-peak fever of the delayed reaction type, reaching its peak in 3 to 4 hours. The results show that certain bacteria probably produce two pyretic substances, one of which, in the viable culture, is dissolved in the medium and stimulates the single-peak fever of the immediate reaction type, and the other is contained mainly in the bacterial cell and stimulates the single-peak fever of the delayed reaction type, a mixture of both causing the double-peak fever. Proteus vulgaris and Ps. fluorescens can produce a volatile depressant substance, which either lowers the body temperature to below normal, or prevents the pyrogen from causing a rise in body temperature. This depressant causes general paralysis if injected in sufficiently large doses, in smaller quantities the most obvious effect is the loss of appetite. It has been shown that any pyrogen test followed by the rabbits refusing to eat for a few days should be examined for other effects of the depressant substance, and should be repeated, taking care to heat the solution to between 30° and 40°C. for about 10 minutes before injection. An investigation of the stability of pyrogen to heat at 120°C. showed that Ps. ***æruginosa, B. subtilis and P. vulgaris produce pyretic substances of similar stability, whereas M. tetragenes produces a much more thermostable substance. The results from the investigation of the stability showed that the pyrogens of P. vulgaris, Ps. æruginosa and B. subtilis are sufficiently labile to require care when using heat during isolation, as approximately 95 per cent. is destroyed after 2 hours at 120°C. Finally it must be emphasised that further investigation into these points would be of little value unless carried out on the pure pyretic substances isolated from various bacterial sources. This work was carried out during the tenure by one of us (D.W.W.) of a Carnegie Scholarship and a Wellcome Research Fellowship to the trustees of which we wish to express our thanks.

A study of the relationship between the fevers caused by bacterial pyrogens and by the intravenous injection of the sterile exudates of acute inflammation

The relationship of the fever caused in rabbits by bacterial pyrogens to the fever produced by the injection of the sterile exudates of acute inflammation was investigated by recording the responses of normal and pyrogen-tolerant animals to injections of exudate. Exudates were produced by the intrapleural injection of turpentine in dogs. The duration of the febrile response in rabbits after a single dose of exudate was found to be much shorter than the fever following an injection of bacterial pyrogen. Animals given daily injections of exudate demonstrated no tolerance to its fever-promoting effect. Animals tolerant to bacterial pyrogens showed no diminution in responsiveness to exudates. Daily injections of exudate failed to establish tolerance to bacterial pyrogens in rabbits. It is concluded that the fever-promoting property of sterile exudates is not due to the presence of bacterial pyrogen.

A study of the relationship between the fever caused by bacterial pyrogens and the fever accompanying acute infections

The relationship between the fever of acute infection and that following injection of bacterial pyrogen was studied by administering pyrogens to animals convalescent from acute infections. Rabbits surviving dermal pneumococcal infections or peritonitis due to Escherichia coli were given intravenous injections of typhoid or E. coli vaccine. They showed no evidence of tolerance to the fever-promoting effect of these pyrogenic materials. Tolerance did develop in infected animals given daily pyrogen injections during the course of the infection. Certain previous observations upon the ability of rabbits to develop tolerance to pyrogens, the broad nature of the tolerance, and its duration were confirmed. It is concluded that the pyrogen produced by certain bacteria plays little or no rôle in the production of the fever of infection. These findings are compatible with the hypothesis that there is a common factor, perhaps a product of cell injury, underlying the fever accompanying diseases of various types.

[Effects of gypsum on the firing of pyrogen-treated thermosensitive neurons in PO/AH of cats]

AIM

To investigate the possible central mechanism of antipyretic effects of Chinese medicine gypsum.

METHODS

Gypsum was injected after the fever model was established. The firing rate of thermosensitive neurons in preoptic-anterior hypothalamus(PO/AH) region was recorded by using extracellular microelectrode technique.

RESULTS

The injection of pyrogen evoked decrease in firing rate of the warm-sensitive neurons and increase in the cold-sensitive neurons in the region of PO/AH; the changes of the firing rate of pyrogen- treated warm-sensitive and cold-sensitive neurons could be reversed by the injection of gypsum.

CONCLUSION

The result may suggest that antipyretic action of gypsum is mediated by its influences on the thermosensitivity neurons in the region of PO/AH.

Effects of electrical stimulation of ventral septal area on firing rates of pyrogen-treated thermosensitive neurons in preoptic anterior hypothalamus from rabbits

Although there is considerable evidence supporting that fever evolved as a host defense response, it is important that the rise in body temperature would not be too high. Many endogenous cryogens or antipyretics that limit the rise in body temperature have been identified. Endogenous antipyretics attenuate fever by influencing the thermoregulatory neurons in the preoptic anterior hypothalamus (POAH) and in adjacent septal areas including ventral septal area (VSA). Our previous study showed that intracerebroventricular (I.C.V.) injection of interleukin-1beta (IL-1beta) affected electrophysiological activities of thermosensitive neurons in VSA regions, and electrical stimulation of POAH reversed the effect of IL-1beta. To further investigate the functional electrophysiological connection between POAH and VSA and its mechanisms in thermoregulation, the firing rates of thermosensitive neurons in POAH of forty-seven unit discharge were recorded by using extracellular microelectrode technique in New Zealand white rabbits. Our results show that the firing rates of the warm-sensitive neurons decreased significantly and those of the cold-sensitive neurons increased in POAH when the pyrogen (IL-1beta) was injected I.C.V. The effects of IL-1beta on firing rates in thermosensitive neurons of POAH were reversed by electrical stimulation of VSA. An arginine vasopressin (AVP) V1 antagonist abolished the regulatory effects of VSA on the firing rates in thermosensitive neurons of POAH evoked by IL-1beta. However, an AVP V2 antagonist had no effects. These data indicated that VSA regulates the activities of the thermosensitive neurons of POAH through AVP V1 but not AVP V2 receptor.

The onset of fever: new insights into its mechanism

The classical view of fever production is that it is modulated in the ventromedial preoptic area (VMPO) in response to signaling by pyrogenic cytokines elaborated in the periphery by mononuclear phagocytes and the consequent induction of cyclooxygenase (COX)-2-dependent prostaglandin (PG)E(2) in the VMPO. This mechanism has, however, been questioned, in particular because the appearance of circulating cytokines lags the onset of the febrile response to intravenously (iv) injected bacterial endotoxic lipopolysaccharide (LPS), an exogenous pyrogen. Moreover, COX-2, in this case, is itself an inducible enzyme, the de novo synthesis of which similarly lags significantly the onset of fever. Issues also exist regarding the accessibility of the POA to blood-borne cytokines. New data adduced over the past 10 years indicate that the peripheral febrigenic message is conveyed to the VMPO via a neural rather than a humoral route, specifically by the vagus to the nucleus tractus solitarius (NST), and that the peripheral trigger is PGE(2), not cytokines; vagal afferents express PGE(2) receptors (EP(3)). Thus, the initiation of the febrile responses to both iv and intraperitoneal (ip) LPS is temporally correlated with the appearance of LPS in the liver's Kupffer cells (Kc), its arrival immediately activating the complement (C) cascade and the consequent production of the anaphylatoxin C5a; the latter is the direct stimulus for PGE(2) production, catalyzed non-differentially by constitutive COX-1 and -2. From the NST, the signal proceeds to the VMPO via the ventral noradrenergic bundle, causing the intrapreoptic release of norepinephrine (NE) which then evokes two distinct core temperature (T(c)) rises, viz., one alpha(1)-adrenoceptor (AR)-mediated, rapid in onset, and PGE(2)-independent, and the other alpha(2)-AR-mediated, delayed, and COX-2/PGE(2)-dependent, i.e., the prototypic febrile pattern induced by iv LPS. The release of NE is itself modulated by nitric oxide contemporaneously released in the VMPO.

Fever and lethargy induced by subcutaneous pyrogen infusion in unrestrained rats

We have investigated the effects of continuous subcutaneous infusion of lipopolysaccharide (LPS), muramyldipeptide (MDP), or saline on abdominal temperature and voluntary activity in unrestrained rats. Both pyrogens were infused via osmotic pumps at a rate of approximately 2 microg.kg-1.min-1 for 7 d. LPS infusion evoked a 3-d and MDP a 1-d elevation in body temperature. Night-time activity was suppressed on days 1 and 2 during LPS infusion and on day 1 of MDP infusion. Body mass was significantly decreased on infusion day 4 in rats receiving either LPS or MDP; however, the rate of weight gain had been restored by day 8 (1 d after cessation of pyrogen infusion). We further tested the body temperature response of the same experimental animals to a single subcutaneous bolus injection (250 microg/kg) of the same pyrogen that had been infused for 7 d, 2 d after cessation of pyrogen infusion (day 9). The fever response in rats receiving a bolus injection of either LPS or MDP was significantly attenuated in rats that had previously been infused with the same pyrogen. These data suggest that tolerance developed to continuous infusion of both Gram-negative and Gram-positive pyrogens, and that mechanisms of tolerance development set in early during the 7-d infusion period of both pyrogens and persisted for at least 2 d after the cessation of pyrogen infusion. We propose that cytokine intermediates were involved or required in inducing these responses to continuous infusion of both LPS and MDP.

The neurobiology of the human febrile response

Fever is a normal adaptation in response to a pyrogenic stimulus resulting in the generation of cytokines and prostaglandins. Fever differs from hyperpyrexia and hyperthermia associated with hot environs and pharmacological triggers. Typically, pyrogens are infectious organisms or their direct products (toxins). The body produces a wide array of pyrogenic cytokines such as interleukins (IL-1, IL-6), interferon, and tumor necrosis factor. Tissue trauma can trigger the febrile response, as can infectious organisms, certain medications, and blood products. The circumventricular organ system (CVOS) is neuronal tissues lying outside the blood-brain barrier that has a key role in initiating the communication sequence responsible for the synthesis of febrile prostaglandins. When pyrogenic cytokines are detected by the CVOS, prostaglandin synthesis, especially cyclooxygenase-dependent prostaglandin E2, is induced, activating the febrile response. Once the appropriate signal is received by the hypothalamus, autonomic, endocrine, and behavioral processes are activated until the hypothalamic set-point is reset downward as a consequence of a reduction in pyrogen content or antipyretic therapy, with subsequent heat loss. There is little evidence that fever facilitates recovery from disease or assists the immune system in mounting a response. Antipyretics are used commonly to decrease the distressing manifestations associated with fever.

Preparation of bupleurum nasal spray and evaluation on its safety and efficacy

Radix Bupleuri is widely used in traditional medicine for the treatment of fever, pain, and inflammation associated with influenza or the common cold. The essential oil extracted from the herb is generally claimed to play the major role in the efficacious treatment of fever. The purpose of the present study was to formulate an intranasal delivery system for the essential oil in an aqueous solution used in the form of nasal spray. From 450 g Radix Bupleuri was extracted the essential oil in the amount of about 0.2 ml, which was slightly water-soluble and viscous with low-fluidity. In order to dissolve the essential oil evenly in the aqueous solution, tween-80 (TW-80, used in 10% (w/v) solution), propylene glycol (PG) and diethylene glycol monoethyl ether (TC) were selected as the favorable solubilizing agents, whose amount was respectively determined by L16(4(5)) orthogonal design. An aqueous solution with clarity and no ciliotoxicity was prepared when TW-80 8% (v/v), PG 14.4% (v/v) and TC 14.4% (v/v) were added. Employed to evaluate the acute toxicity, the rats grew well and were kept active and healthy within 14 d after an intranasal administration of this preparation at the dose of oil from 10 g Bupleuri/kg (50-fold higher than the clinical dose), indicating that there would be no serious toxicity at the normal dose. Intranasal administration of this preparation to 2 kg rabbits with fever induced by subcutaneous injection of turpentine decreased body temperature markedly (0.5, 0.8 and 1.0 degrees C respectively at the dose of oil from 1, 2 and 4 g Bupleuri/body). In addition, the administration significantly reduced fever in 200 g rats induced by intramuscular injection of colicine suspension (0.6 degrees C at the dose of oil from 0.8 g Bupleuri/body). The results suggest that the formulation of nasal spray for the essential oil from Radix Bupleuri can be potentially effective in the treatment of fever.

Dry and moist heat sterilisation cannot inactivate pyrogenicity of Gram positive microorganisms

In the monocytic cell line Mono Mac 6 pyrogens induce interleukin-6 secretion dose dependently. The aim of this study is to examine the interleukin-6 inducing capacity of Gram positive Staphylococcus aureus and Bacillus subtilis endospores after moist and dry heat sterilisation. Moist heat sterilisation of B. subtilis endospores for 15 min at 121 degrees C and 134 degrees C can only reduce the interleukin-6 inducing capacity to 57% and 63%, respectively, compared to untreated. Moist heat sterilisation of S. aureus for 60 min at 121 degrees C and 134 degrees C does not reduce the interleukin-6 inducing capacity of S. aureus. On the contrary moist heat sterilisation at 134 degrees C for 10, 20 and 40 min significantly increases the interleukin-6 inducing capacity compared to untreated S. aureus. This is confirmed in the rabbit pyrogen test. Dry heat sterilisation of B. subtilis endospores at 220 degrees C for 45 min reduces the interleukin-6 inducing capacity to 2% compared to untreated endospores. Dry heat treatment of S. aureus at 220 degrees C for 30 min only reduces the activity to 55%. However, after 250 degrees C for 30 min or 220 degrees C for 6h there is no detectable activity of S. aureus. In conclusion, neither the interleukin-6 inducing activity nor the pyrogenicity of S. aureus and endospores of B. subtilis can be inactivated by the heat sterilisation procedures described by the European Pharmacopoeia.

Studies on the antipyretic action of cortisone in pyrogen-induced fever

The mode of action of cortisone as an antipyretic has been studied in rabbits challenged with intravenous injections of bacterial pyrogens. The fever induced by pyromen or dextran was found to be markedly suppressed when cortisone was administered in liberal amounts (25 mg. twice daily) for 3 days prior to the challenge. Although the cortisone effectively blocked the febrile response to both pyrogens, it failed to influence the transient but marked leucopenia which characteristically precedes the onset of fever. The antipyretic action of the drug also was shown to bear no relation to the activity of the serum factor recently demonstrated by Farr, Grant, and others to be involved in the production of pyrogen-induced fever. In preliminary experiments with typhoid vaccine as the inciting pyrogen, the presence of serum factor activity in normal blood and its absence in the blood of pyrogen-tolerant rabbits was confirmed. Subsequently the blood of rabbits treated with antipyretically effective doses of cortisone was shown to contain just as much serum factor activity as that of normal rabbits. In addition, previous incubation of the pyrogen with serum factor failed to influence the antipyretic effect of the drug. It is concluded from these findings that in suppressing pyrogen fever, cortisone acts neither upon the leucopenic reaction nor upon the fever-accelerating factor of the serum. By exclusion it would appear that the drug must influence some later stage of the fever-producing process. The mechanisms involved in the later stages of the response to exogenous pyrogen remain undefined, and the need for determining whether they are related to the prefebrile leucopenia is emphasized.

Studies on the pathogenesis of fever. I. The presence of transferable pyrogen in the blood stream following the injection of typhoid vaccine

The rate of clearance of intravenously injected typhoid vaccine was studied in unsensitized, sensitized, and pyrogen-tolerant rabbits by means of a passive transfer technique. The blood of unsensitized rabbits which had not been previously exposed to bacterial pyrogen remained pyrogenic for normal recipients throughout a period of 2 hours following the injection. In contrast, rabbits sensitized by having received either one or two injections of the vaccine at least 3 weeks prior to the experiment cleared their blood of the test vaccine within 30 minutes despite the fact that they exhibit the same febrile response as unsensitized rabbits. After 1 hour, however, a transferable pyrogenic substance was again demonstrable in the sera of this group. Reasons are discussed for believing that this newly appearing substance may be of endogenous origin and may be the factor which directly affects the thermoregulatory centers of the brain. Rabbits which are made tolerant by repeated daily injections of vaccine have a characteristically depressed febrile response. Not only were the blood streams of such animals cleared of the injected vaccine within less than 5 minutes, but samples of their sera obtained 1 and 2 hours after the injection also failed to contain demonstrable quantities of the secondary pyrogen observed in sensitized animals. The latter observation is in keeping with the suggestion that the secondary pyrogen may play a critical role in the production of fever.