Synthesis and evaluation of tylosin-related macrolides modified at the aldehyde function: a new series of orally effective antibiotics.

Modification of the aldehyde group in tylosin and related macrolide antibiotics dramatically enhanced the oral efficacy of the derivatives against experimental infections caused by susceptible bacteria in laboratory animals. A large number and wide variety of aldehyde-modified macrolide derivatives were prepared, utilizing the Mitsunobu reaction and other chemical transformations. Evaluation of in vitro and in vivo antimicrobial activity indicated that derivatives of demycarosyltylosin (desmycosin) combined the broadest spectrum of antimicrobial activity with the best efficacy and bioavailability after oral administration.

In vitro and in vivo evaluation of C-20- and C-23-modified derivatives of tylosin against veterinary pathogens.

Three series of semi-synthetic derivatives of tylosin-related macrolides were evaluated for utility in veterinary medicine. 23-Modified derivatives of 5-O-mycaminosyltylonolide (OMT) possessed potent activity in vitro against species of Pasteurella and Mycoplasma. An experimental infection in chicks caused by Pasteurella multocida was utilized to evaluate efficacy; several of these derivatives of OMT effectively treated the infection when given subcutaneously, but none were effective after oral administration in drinking water. Macrolides retaining the 4'-O-mycarosyl moiety (tylosin, DMT) had relatively poor activity against Pasteurella in vitro. Certain 20-modified derivatives of desmycosin demonstrated good oral bioavailability in chicks and a lead compound with oral efficacy in the Pasteurella infection model was discovered.

Synthesis and antimicrobial evaluation of acyl derivatives of 16-membered macrolide antibiotics related to tylosin.

A large number and wide variety of acyl derivatives of the tylosin-related macrolides 23-demycinosyltylosin (DMT), 23-demycinosyloxytylosin (DMOT) and 5-O-mycaminosyltylonolide (OMT) were synthesized and evaluated. This encompassed conversion of the hydroxyl groups at 2',4' and 23 of the appropriate macrolides to the corresponding esters, in which a variety of different substitution patterns were examined. A wide range of acyl substituents was investigated, particularly for 23-O-acyl derivatives of OMT, since these were substantially more active in vitro than OMT itself. However, the acyl derivatives which were prepared demonstrated no substantial improvement in oral efficacy or bioavailability over the parent macrolides.

Treatment of experimental Haemophilus influenzae type b meningitis with 1-oxa-beta-lactam (LY127935).

1-Oxa-beta-lactam (LY127935) (Shionogi 6059-S) is a new type beta-lactam antibiotic having a broad spectrum of antibacterial activity. It is highly active against ampicillin-resistant strains of Haemophilus influenzae exhibiting minimal inhibitory concentrations as low as 0.06 microgram/ml. This compound also has the ability to penetrate into the cerebrospinal fluid of both normal and infected infant rats and attains approximately 10% of the corresponding blood levels. LY127935 was evaluated for its ability to treat ampicillin-resistant H. influenzae meningitis in an established experimental model using infant rats. Rats with ampicillin-resistant H. influenzae meningitis were treated subcutaneously three times daily for 2 days with various dose levels of LY127935. When given in doses as low as 10 mg/kg, LY127935 sterilized the blood and cerebrospinal fluid in all rats examined at 1 and 5 days posttreatment. In contrast, ampicillin was not effective at this dose in eliminating H. influenzae from the blood and cerebrospinal fluid of infected rats. LY127935 was effective against experimental ampicillin-resistant H. influenzae meningitis in the dosages employed.

Abnormal cellular immune responses during acquired zinc deficiency.

The cellular immune response of a 17-year-old decerebrate male with acquired zinc deficiency was studied. He had been fed a commercial formula which contained 7.6 mg zinc per kilogram. His caloric intake had been inadequate as judged by his cachexia. A detailed pretreatment nutritional assessment (five separate observations) which included total serum protein and globulins, albumin, folate, vitamins A, B2, C, ceruloplasmin, and plasma zinc, copper, iron, and total iron binding capacity revealed that the patient was deficient only in zinc and calories. His plasma zinc was 41 +/- 5 microgram/d1 compared with our laboratory norm of 89 +/- 9 microgram/d1 for young adult males. Cellular immunity was assessed by delayed skin reactivity to dinitrochlorobenzene and by in vitro lymphocyte transformation studies. Before zinc therapy the patient rendered a negative skin reaction to dinitrochlorobenzene, and the ability of his lymphocytes to undergo blast transformation in response to mitogen stimulation was significantly depressed with a stimulation index of 4.7 +/- 0.8 as compared with 139.1 +/- 77.3 for controls. Within 3 weeks after zinc therapy (22.7 mg zinc per day) he demonstrated a positive delayed skin reaction to dinitrochlorobenzene and a normal lymphocyte response stimulation index = 205.5 +/- 42.6 versus 199.3 +/- 58.2 for control). In addition, a pretreatment facial seborrhea and a decubitus ulcer rapidly healed.

Leukocytic endogenous mediator in Crohn's disease.

Reduced concentrations of plasma zinc associated with elevated levels of serum leukocytic endogenous mediator activity were found in 17 patients hospitalized with acute exacerbation of Crohn's disease. Neither the decrease in plasma zinc nor the increase in leukocytic endogenous activator activity in nine outpatients with quiescent disease was significant. Leukocytic endogenous mediator activity may be increased in inflammatory conditions as well as in microbial infections. Although zinc deficiency may be common in patients with Crohn's disease, exclusive reliance on circulating zinc levels to assess zinc nutriture in active Crohn's disease may be misleading.

Effect of leukocytic endogenous mediator (LEM) on zinc absorption in the rat.

Leukocytic endogenous mediator (LEM) was shown to produce a significant increase in the intestinal absorption of zinc within 7 hr after its administration to normal rats. Consistent with earlier studies, LEM also produced a significant decrease in the plasma zinc concentration and an increased hepatic uptake of this metal which further demonstrates that LEM may be a key intermediate in altering zinc homeostasis during inflammation.

Protein synthesis in zinc deficient rats during tularemia.

The effect of zinc deficiency on protein synthesis in rats during tularemia was studied. Five weeks prior to infection with the live vaccine strain of Francisella tularensis, rats had been assigned to one of three dietary groups: zinc deficient (-Zn), pair-fed (PF) or ad libitum (AL). Within 4 weeks, zinc deficiency manifested itself by diminished growth rate, decreased serum and liver zinc concentrations and alopecia. By 18 hour post infection, rats of all groups were febrile and exhibited an increased hepatic uptake of zinc. Despite initially lower concentrations of seromucoid in the PF and -Zn groups, infection elicited an increase in seromucoid concentration as well as enhanced incorporation of 3H-leucine into this fraction of comparable degree in all dietary groups. The same held true for ceruloplasmin. Alpha 2-macrofetoprotein also increased to the same extent in all dietary groups. Infection was associated with a decrease in extractable albumin in ad libitum and pair fed control groups. Only the -Zn group showed a significant decrease in specific activity suggestive of diminished albumin synthesis. Zinc deficiency of itself did not cause a decrement in radiolabel in muscle protein. Thus, despite documented zinc deficiency, rats subjected to the stress of infection respond by synthesizing increased amounts of acute phase globulins apparently at the expense of serum albumin and muscle protein synthesis.

Effect of acute infection and endotoxemia on zinc absorption in the rat.

Intestinal zinc absorption was found to be significantly increased during acute bacterial infection and endotoxemia in the rat. Although serum zinc concentrations were depressed, there was a significant accumulation of 65Zn in the livers of the stressed animals. This study demonstrates that acute inflammation produces a redistribution of zinc within the host, which results in both increased zinc absorption and retention.

Induced metabolic sequelae of tularemia in the rat: correlation with tissue damage.

Serum and liver zinc concentration, amino acid uptake by liver, seromucoid content, and alpha2-macrofetoprotein production were measured in vaccinated as well as nonimmune rats exposed to either virulent (SCHU S4) or attenuated (LVS) strains of Francisella tularensi. It appears that liver damage (pyogranulomatous lesions) must occur before there is any alteration in the above variables. The presence of bacteria in the liver is not of itself sufficient to lead to the onset of systemic, induced metabolic sequelae (IMS). The occurrence of zinc redistribution in all instances of increased serum protein synthesis may imply a necessary relationship between these two sequelae. Amino acid redistribution does not appear to be linked to serum protein synthesis. An endogenous mediator of systemic IMS can be detected in tularemic rats by injection of the serum of these animals into healthy recipients. The occurrence of zinc redistribution and increased serum protein synthesis in some groups of rats in the absence of amino acids uptake by liver, as well as the apparent differential dose responsiveness of these responses, are suggestive of a multiplicity of endogenous mediators.

Detection of a leukocytic endogenous mediator-like mediator of serum amino acid and zinc depression during various infectious illnesses.

Serum samples from patients with many different kinds of infection were shown to contain a substance characteristic of leukocytic endogenous mediator. Generalized bacterial infections produced more leukocytic endogenous mediator than did localized ones; viral infections produced very little. In typhoid fever, mediator concentrations increased before the onset of illness.

Serum zinc, iron, and copper concentrations during typhoid fever in man: effect of chloramphenicol therapy.

In volunteers experimentally infected with Salmonella typhi, serum iron and zinc concentrations became significantly depressed and there was a concomitant rise in serum copper before the onset of overt clinical illness. However, after several days of fever and the initiation of chloramphenicol therapy, serum iron and zinc concentrations significantly increased. Additional studies--in volunteers with typhoid fever treated with chloramphenicol, in a volunteer with typhoid fever receiving cefazolin and gentamicin, and in untreated rhesus monkeys infected with Salmonella typhimurium--provided evidence that the increase in serum iron concentration during the febrile phase was the result of chloramphenicol therapy, whereas the increase in serum zinc concentrations was a disease-related phenomenon. The importance of trace-metal monitoring during infectious disease and chemotherapy is discussed.

Relationship between serum chromium concentrations and glucose utilization in normal and infected subjects.

Studies in healthy individuals demonstrate that serum chromium concentrations fall precipitiously following the intravenous administration of a 30-gm. glucose load. Significant decreases from baseline control fasting serum Cr concentrations were also observed when intravenous glucose was given during sandfly fever. Glucose disappearance rates also decreased significantly to approximately one half of pre-illness control values while serum Cr values declined still further. In addition, serum Cr disappearance rates could be calculated. When individual preexposure and postexposure serum glucose and Cr disappearance rates were compared, significant linear correlation was found (P smaller than 0.05). Acute infection appears to reduce the availability of circulating Cr, which may contribute to the altered glucose metabolism characteristic of acute infections even in the presence of elevated insulin levels and other hormonal changes.

A protein from polymorphonuclear leukocytes (LEM) which affects the rate of hepatic amino acid transport and synthesis of acute-phase globulins.

A proteinaceous secretion from phagocytizing polymorphonuclear leukocytes, termed "leukocytic endogenous mediator" (LEM), has been shown to have marked effects on hepatic amino acid transport and RNA and protein synthesis. A single injection of LEM results in a marked accumulation of labeled nonmetabolizable model amino acids in the liver of normal rats. The LEM-stimulated uptake of amino acids by liver was observed in adrenalectomized, hypophysectomized, thyroidectomized, or diabetic rats and could not be duplicated by pharmacological doses of a large variety of hormones. In addition, LEM stimulated an increased uptake of alpha-aminoisobutyric acid by isolated livers during their perfusion in vitro. LEM also stimulated an increased incorporation of orotic acid into hepatic RNA of intact rats, especially into the bound ribosomal fraction. This increased synthesis of RNA preceded an enhanced hepatic production of a number of the acute-phase plasma globulins. LEM did not stimulate the adenylate cyclase-cAMP system in liver and was not found to utilize this system as a second messenger. Thus, the effects of LEM in stimulating hepatic amino acid transport appear to be direct, without mediation by other hormones, and to be independent of cAMP. On the other hand, the ability of LEM to stimulate RNA and acute phase globulin synthesis in liver may require the presence of physiological quantities of hormones such as adrenal corticoids.