The effect of amphotericin B, aztreonam, imipenem and cephalosporins on the bone marrow progenitor cell activity

Targeting gut microbial nitrogen recycling and cellular uptake of ammonium to improve bortezomib resistance in multiple myeloma

The gut microbiome has been found to play a crucial role in the treatment of multiple myeloma (MM), which is still considered incurable due to drug resistance. In previous studies, we demonstrated that intestinal nitrogen-recycling bacteria are enriched in patients with MM. However, their role in MM relapse remains unclear. This study highlights the specific enrichment of Citrobacter freundii (C. freundii) in patients with relapsed MM. Through fecal microbial transplantation experiments, we demonstrate that C. freundii plays a critical role in inducing drug resistance in MM by increasing levels of circulating ammonium. The ammonium enters MM cells through the transmembrane channel protein SLC12A2, promoting chromosomal instability and drug resistance by stabilizing the NEK2 protein. We show that furosemide sodium, a loop diuretic, downregulates SLC12A2, thereby inhibiting ammonium uptake by MM cells and improving progression-free survival and curative effect scores. These findings provide new therapeutic targets and strategies for the intervention of MM progression and drug resistance.

Alphataxin, an Orally Available Small Molecule, Decreases LDL Levels in Mice as a Surrogate for the LDL-Lowering Activity of Alpha-1 Antitrypsin in Humans

The abundant blood protein α1-proteinase inhibitor (α1PI, Αlpha-1, α1-antitrypsin, SerpinA1) is known to bind to the active site of granule-associated human leukocyte elastase (HLE-G). Less well known is that binding of α1PI to cell surface HLE (HLE-CS) induces lymphocyte locomotion mediated by members of the low density lipoprotein receptor family (LDL-RFMs) thereby facilitating low density lipoprotein (LDL) clearance. LDL and α1PI were previously shown to be in negative feedback regulation during transport and clearance of lipoproteins. Further examination herein of the influence of α1PI in lipoprotein regulation using data from a small randomized, double-blind clinical trial shows that treatment of HIV-1-infected individuals with α1PI plasma products lowered apolipoprotein and lipoprotein levels including LDL. Although promising, plasma-purified α1PI is limited in quantity and not a feasible treatment for the vast number of people who need treatment for lowering LDL levels. We sought to develop orally available small molecules to act as surrogates for α1PI. Small molecule β-lactams are highly characterized for their binding to the active site of HLE-G including crystallographic studies at 1.84 Å. Using high throughput screening (HLE-G inhibition, HLE-CS-induced cellular locomotion), we show here that a panel of β-lactams, including the LDL-lowering drug ezetimibe, have the capacity to act as surrogates for α1PI by binding to HLE-G and HLE-CS. Because β-lactams are antibiotics that also have the capacity to promote evolution of antibiotic resistant bacteria, we modified the β-lactam Alphataxin to prevent antibiotic activity. We demonstrate using the diet-induced obesity (DIO) mouse model that Alphataxin, a penam, is as effective in lowering LDL levels as FDA-approved ezetimibe, a monobactam. Non-antibiotic β-lactams provide a promising new therapeutic class of small molecules for lowering LDL levels.

Diagnosis and Surgical Management of a Paratesticular Cyst in a Rehabilitating Juvenile Male Green Turtle (Chelonia mydas)

A juvenile green turtle (Chelonia mydas) undergoing rehabilitation for cold stunning exhibited an asymmetric bulging of the left caudal plastron and was diagnosed with a large intra-coelomic mass based on radiographical findings. Ultrasonography further identified a fluid-filled structure within the caudal coelom. Cytological evaluation of fluid obtained from the structure was consistent with a transudate, and thus, a cyst of unknown origin was suspected. Computed tomography imaging was pursued to further characterize the extent and location of the mass, which occupied ~50% of the total coelomic cavity volume. Conservative management with monitoring and occasional drainage of the mass did not result in improvements; thus, an exploratory laparoscopy for further investigation and surgical planning was elected. Intra-coelomic surgery was performed to remove a thick-walled cystic mass associated with the left gonad. Histopathology confirmed a paratesticular cyst continuous with, and possibly originating from, the epididymis. Post-surgical recurrence of the cyst was not appreciated, and the animal was successfully released 1 year after admission. Unrelated to the cyst, the turtle developed acute severe anemia on two occasions throughout rehabilitation that responded to modification of antimicrobial treatment and subsequent steroid administration. To the authors' knowledge, this is the first report of a paratesticular cyst in a reptile.

Early local delivery of vancomycin suppresses ectopic bone formation in a rat model of trauma-induced heterotopic ossification

Heterotopic ossification (HO) is a debilitating sequela of high-energy injuries. It frequently requires surgical excision once symptomatic and there is no practical prophylaxis for combat-injured patients. In this study, we examined the effect of local vancomycin powder on HO formation in a small animal model of blast-related, post-traumatic HO. Male Sprague-Dawley rats were subjected to a polytraumatic extremity injury and amputation with or without methicillin-resistant Staphylococcus aureus infection. Animals were randomized to receive a single local application of vancomycin (20 mg/kg) at the time of injury (POD-0, n = 34) or on postoperative day-3 (POD-3, n = 11). Quantitative volumetric measurement of ectopic bone was calculated at 12-weeks post-injury by micro-CT. Bone marrow and muscle tissues were also collected to determine the bacterial burden. Blood for serum cytokine analysis was collected at baseline and post-injury. Vancomycin treatment on POD-0 suppressed HO formation by 86% and prevented bone marrow and soft tissue infections. We concurrently observed a marked reduction histologically in nonviable tissue, chronic inflammatory cell infiltrates, bone infection, fibrous tissue, and areas of bone necrosis within this same cohort. Delayed treatment was significantly less efficacious. Neither treatment had a marked effect on the production of pro-inflammatory cytokines. Our study demonstrates that local vancomycin treatment at the time of injury significantly reduces HO formation in both the presence and absence of infection, with decreased efficacy if not given early. These findings further support the concept that the therapeutic window for prophylaxis is narrow, highlighting the need to develop early treatment strategies for clinical management. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2397-2406, 2017.

Cinnamaldehyde and its derivatives, a novel class of antifungal agents

The last few decades have seen an alarming rise in fungal infections, which currently represent a global health threat. Despite extensive research towards the development of new antifungal agents, only a limited number of antifungal drugs are available in the market. The routinely used polyene agents and many azole antifungals are associated with some common side effects such as severe hepatotoxicity and nephrotoxicity. Also, antifungal resistance continues to grow and evolve and complicate patient management, despite the introduction of new antifungal agents. This suitation requires continuous attention. Cinnamaldehyde has been reported to inhibit bacteria, yeasts, and filamentous molds via the inhibition of ATPases, cell wall biosynthesis, and alteration of membrane structure and integrity. In this regard, several novel cinnamaldehyde derivatives were synthesized with the claim of potential antifungal activities. The present article describes antifungal properties of cinnamaldehyde and its derivatives against diverse classes of pathogenic fungi. This review will provide an overview of what is currently known about the primary mode of action of cinnamaldehyde. Synergistic approaches for boosting the effectiveness of cinnamaldehyde and its derivatives have been highlighted. Also, a keen analysis of the pharmacologically active systems derived from cinnamaldehyde has been discussed. Finally, efforts were made to outline the future perspectives of cinnamaldehyde-based antifungal agents. The purpose of this review is to provide an overview of current knowledge about the antifungal properties and antifungal mode of action of cinnamaldehyde and its derivatives and to identify research avenues that can facilitate implementation of cinnamaldehyde as a natural antifungal.

Modulation of dendritic cell differentiation in the bone marrow mediates sustained immunosuppression after polymicrobial sepsis

Murine polymicrobial sepsis is associated with a sustained reduction of dendritic cell (DC) numbers in lymphoid organs and with a dysfunction of DC that is considered to mediate the chronic susceptibility of post-septic mice to secondary infections. We investigated whether polymicrobial sepsis triggered an altered de novo formation and/or differentiation of DC in the bone marrow. BrdU labeling experiments indicated that polymicrobial sepsis did not affect the formation of splenic DC. DC that differentiated from bone marrow (bone marrow-derived DC [BMDC]) of post-septic mice released enhanced levels of IL-10 but did not show an altered phenotype in comparison with BMDC from sham mice. Adoptive transfer experiments of BMDC into naive mice revealed that BMDC from post-septic mice impaired Th1 priming but not Th cell expansion and suppressed the innate immune defense mechanisms against Pseudomonas bacteria in the lung. Accordingly, BMDC from post-septic mice inhibited the release of IFN-γ from NK cells that are critical for the protection against Pseudomonas. Additionally, sepsis was associated with a loss of resident DC in the bone marrow. Depletion of resident DC from bone marrow of sham mice led to the differentiation of BMDC that were impaired in Th1 priming similar to BMDC from post-septic mice. Thus, in response to polymicrobial sepsis, DC precursor cells in the bone marrow developed into regulatory DC that impaired Th1 priming and NK cell activity and mediated immunosuppression. The absence of resident DC in the bone marrow after sepsis might have contributed to the modulation of DC differentiation.

An overview of harms associated with beta-lactam antimicrobials: where do the carbapenems fit in?

The US Institute of Medicine's focus on patient safety has motivated hospital administrators to facilitate a culture of safety. As a result, subcommittees of the pharmacy and therapeutics committee have emerged in many hospitals to focus on adverse events and patient safety. Antimicrobial harms have gained the attention of practicing clinicians and hospital formulary committees, because they top the list of drugs that are associated with adverse events and because of certain serious harms that have ultimately led to the withdrawal of some antimicrobial agents. In the near future, several antimicrobials in the late phase of development will become available for clinical use (ceftobiprole, ceftaroline, and telavancin), and others (doripenem and dalbavancin) have recently joined the armamentarium. Because new antimicrobials will become part of the treatment armamentarium, it is important to discuss our current understanding of antimicrobial harms in general. Although not thought of as traditional adverse events, Clostridium difficile infection and development of resistance during therapy are adverse events that occur as a result of antimicrobial exposure and therefore are discussed. In addition, a distillation of our current understanding of β-lactam specific adverse events will be provided. Finally, new methods of administration are being evaluated that may influence peak concentration-related antimicrobial adverse events.

Toward refinement of the colony-forming unit-granulocyte/macrophage clonogenic assay: Inclusion of a metabolic system

This work represents a first attempt to refine the colony-forming unit-granulocyte/macrophage (CFU-GM) clonogenic assay by incorporating liver microsomes and co-factors as a metabolic system into the in vitro test system in response to an ECVAM recommendation. From the comparison of results obtained with the CFU-GM clonogenic assay currently used and with the new experimental protocol, different toxicity on granulocyte/macrophage precursors was demonstrated, when drugs with a known metabolism in vivo were tested.

Neutropenia secundaria a betalactámicos. Una vieja compañera olvidada

Beta-lactam-induced neutropenia has been a well-recognized problem since the initiation of penicillin use. It generally develops following high-dose beta-lactam treatment lasting longer than 10 days, and its frequency rises with increases in the cumulative antibiotic dose. Beta-lactam-induced neutropenia is frequently preceded by fever or rash, which can be considered alarm signs. Unlike neutropenia induced by other nonchemotherapy drugs, beta-lactam-induced neutropenia usually lasts less than 10 days and infrequently causes infectious complications or death. Although any beta-lactam agent can cause neutropenia, recent studies have focused on cases of piperacillin-tazobactam- or cefepime-induced neutropenia; a high incidence of neutropenia has been demonstrated during prolonged treatment with these antibiotics. The apparent contradiction with the results of clinical trials that did not detect this complication is due to the fact that they involved treatments shorter than two weeks. The potential for the development of neutropenia during lengthy intravenous treatment should be borne in mind in the development of new beta-lactams.

Deproteinized bovine bone and gentamicin as an adjunct to GTR in the treatment of intrabony defects: a randomized controlled clinical study

OBJECTIVES

To evaluate whether Bio-Oss used as an adjunct to guided tissue regeneration (GTR) improves the healing of 1- or 2-wall intrabony defects as compared with GTR alone, and to examine whether impregnation of Bio-Oss with gentamicin may have an added effect.

MATERIAL AND METHODS

Sixty patients, with at least one interproximal intrabony defect with probing pocket depth (PPD) > or =7 mm and radiographic evidence of an intrabony component (IC) > or =4 mm, were treated at random with either a resorbable membrane (GTR), a resorbable membrane in combination with Bio-Oss impregnated with saline (DBB-), a resorbable membrane in combination with Bio-Oss impregnated with gentamicin (DBB+), or with flap surgery (RBF).

RESULTS

All treatment modalities resulted in statistically significant clinical improvements after 1 year. Defects treated with GTR alone presented a probing attachment level (PAL) gain of 2.9 mm, a residual PPD (PPD12) of 4.9 mm, a radiographic bone level (RBL) gain of 3.1 mm, and a residual IC (IC12) of 2.7 mm. GTR combined with Bio-Oss did not improve the healing outcome (PAL gain: 2.5 mm; PPD12: 4.9 mm; RBL gain: 2.8 mm; IC12: 3.3 mm). Impregnation of the Bio-Oss with gentamicin 2% mg/ml resulted in clinical improvements (PAL gain: 3.8 mm; PPD12: 4.2 mm; RBL gain: 4.7 mm; IC12: 2.1 mm), superior to those of the other treatment modalities, but the difference was not statistically significant. Defects treated with only flap surgery showed the most inferior clinical response (PAL gain: 1.5 mm; PPD12: 5.1 mm; RBL gain: 1.2 mm; IC12: 4.2 mm) of all groups.

CONCLUSION

The results failed to demonstrate an added effect of Bio-Oss implantation in combination with GTR on the healing of deep interproximal 1- or 2-wall, or combined 1- and 2-wall intrabony defects compared with GTR alone. Local application of gentamicin, on the other hand, improved the treatment outcome but not to an extent that it was statistically significant.

Gentamicin used as an adjunct to GTR

OBJECTIVES

To evaluate in a discriminating "capsule" model whether local application of gentamicin may have an added effect on bone formation produced by Bio-Oss and guide tissue regeneration (GTR).

MATERIAL AND METHODS

Thirty male 3-month-old Wistar rats were used. After elevation of muscle-periosteal flaps, a rigid hemispherical Teflon capsule, loosely packed with 0.025 g of Bio-Oss impregnated with 2 mg/ml gentamicin sulfate (Garamycin), was placed with its open part facing the lateral bone surface of the mandibular ramus (test) in one side of the jaw. A capsule filled only with Bio-Oss (control) was placed on the contralateral side of the jaw. After healing periods of 1, 2 and 4 months, groups of 10 animals were sacrificed and the specimens were processed for histological examination. The volumes of (1) the space created by the capsule, (2) newly formed bone, (3) Bio-Oss particles, (4) loose connective tissue, and (5) acellular space in the capsule were estimated by a point-counting technique in three to four histological sections of each specimen, taken by uniformly random sampling.

RESULTS

The histological evaluation showed limited but increasing bone fill in the capsules from 1 to 4 months in both the test and control sides. After 4 months, the newly formed bone occupied 11.9% (CV: 0.39) of the space created by the capsules at the test sides versus 13.2% (CV: 0.41) at the control sides. There was no statistical significant difference between test and control specimens at any observation time (p>0.05).

CONCLUSION

It is concluded that local application of gentamicin has no added effect on bone formation when combined with Bio-Oss and GTR.

Difference in the responses after administration of granulocyte colony-stimulating factor in septic patients with relative neutropenia

OBJECTIVE

The objective of this study was to classify the clinical responses after administration of granulocyte colony-stimulating factor (G-CSF) in septic patients with relative neutropenia.

PATIENTS AND METHODS

We administered recombinant human G-CSF (2 microg/kg) subcutaneously once a day for 5 days to 30 septic patients with white cell counts below 5,000 cells/mm3. Absolute neutrophil count (ANC), neutrophil differentiation, and serum concentration of G-CSF were determined serially. Bone marrow also was analyzed before and after treatment.

RESULTS

Neutrophil responses to G-CSF varied from good (ANC > 10,000/mm3, group G, n = 20) to moderate (ANC < 10,000/mm3, group M, n = 5) to poor (no increase in ANC, group P, n = 5). Before G-CSF administration, the three groups showed no differences in ANC but did show significant differences in serum concentration of G-CSF. G-CSF concentration was 0.16 +/- 0.03 ng/mL in group G, 7.0 +/- 3.0 ng/mL in group M, and 270 +/- 90 ng/mL in group P. Immature neutrophils accounted for 35.0 +/- 3.7% of peripheral leukocytes in group P but only 5.1 +/- 0.6% in group G. Although bone marrow was depressed in all groups before G-CSF treatment, nucleated cell count increased significantly after rhG-CSF treatment in groups G and M. Survival rate after 4 weeks was 90% in group G and 100% in group M; no patient in group P survived.

CONCLUSION

G-CSF administration was effective in septic patients with a low percentage of immature neutrophils and insufficient endogenous G-CSF. It had little effect on patients with a high percentage of immature neutrophils whose G-CSF production was up-regulated and whose bone marrow was severely depressed.

Protective effect of granulocyte-colony stimulating factor against amphotericin B-induced myelosuppression in vitro

Amphotericin B causes suppression of bone marrow (BM) progenitor cells in vitro. Granulocyte colony stimulating factor (G-CSF) enhances the proliferation of myeloid cells. The present study defines the role of G-CSF in preventing amphotericin B-induced myelosuppression. G-CSF increased the proliferative potential of BM and protected against amphotericin B-induced myelosuppression if it was added to the medium during the early phase of exposure of BM to amphotericin B. Monoclonal antibodies to tumour necrosis factor-alpha (TNF) or interferon-gamma (IFN) inhibited the myelosuppression partially; simultaneous presence of both these antibodies completely abrogated this suppression, suggesting that both TNF alpha and IFN gamma were involved in amphotericin-induced myelosuppression. TNF- or IFN-induced suppression of BM was also inhibited by G-CSF. These data suggest that G-CSF prevents the amphotericin B-induced myelosuppression by antagonizing the suppressive effects of TNF and IFN and by enhancing the proliferative activity of BM.

Beta-Lactam antibiotic-induced leukopenia in severe hepatic dysfunction: risk factors and implications for dosing in patients with liver disease

PURPOSE

To determine if an association could be established for leukopenia and administration of beta-lactam antibiotic therapy in patients with hepatic dysfunction. If such an association could be found, to determine the incidence, timing, and risk factors for beta-lactam antibiotic-induced leukopenia.

PATIENTS AND METHODS

Patients with hepatic dysfunction, i.e., liver transplant recipients as well as patients with end-stage liver disease awaiting liver transplantation, seen at our institution between October 1989 and October 1991, who received 7 or more days of antibiotics, were studied in a prospective observational fashion. Complete blood count was determined at baseline and followed until the completion of the antibiotic course or until the resolution of leukopenia in leukopenic patients.

RESULTS

Leukopenia occurred after a mean of 6 days with 23% of the beta-lactam antibiotic courses as compared with 0% with the non-beta-lactam antibiotic courses (p = 0.046). Development of leukopenia correlated with the severity of liver disease. Patients developing leukopenia had worse synthetic hepatic function as evidenced by a lower serum albumin level (p < 0.01), a lower serum cholesterol level (p < 0.05), and a higher prothrombin time (p < 0.01) as compared with the patients without leukopenia. Leukopenic patients had a lower baseline white blood cell count (p < 0.051) and a lower baseline platelet count (p < 0.01) indicative of a greater degree of hypersplenism. Leukopenic patients received a higher mean daily dosage of cephalosporins as compared with nonleukopenic patients.

CONCLUSION

beta-Lactam antibiotics when administered in usually recommended dosages can induce leukopenia in patients with hepatic dysfunction. The probable mechanism is impaired hepatic metabolism of the beta-lactam antibiotics resulting in bone marrow suppression of white cell precursors from excessive antibiotic concentrations. The more severe the hepatic dysfunction, the greater the risk. We propose a reduction in dosages of beta-lactam antibiotics when used in patients with hepatic dysfunction. Finally, we raise the possibility that this adverse drug effect is more common than currently recognized by physicians.