Spontaneous use of matching visual cues during foraging by long-tailed macaques (Macaca fascicularis)

A social group of 38 captive-born Macaca fascicularis was confined to a holding cage while food was placed in an outdoor enclosure next to a structure (e.g., stone, tree) that varied across trials. After the group was released and obtained the food, animals inspected other structures similar to the baited structure more quickly and more often than they inspected equally conspicuous nonmatching structures. Animals also varied their search according to the quality of food, remembered the exact location of food on the previous trial, and discriminated sharply between locations where other macaques found or did not find food. Use of visual cues by experimentally naive macaques seems far more efficient than would be expected from many prior laboratory studies but is consistent with wild macaque foraging behavior.     

Sonographic heat generation in vivo in the gravid long-tailed macaque (Macaca fascicularis)

Temperature elevations that occur during diagnostic ultrasonic exposure were assessed in vivo in gravid macaques after 10, 20, or 30 min (scan mode; N = 30) or 5, 10, or 15 min (pulsed Doppler; N = 32). Five time points were assessed during the second and third trimesters (gestational days 70 to 150 +/- 2; term, approximately 165 days) using a transient thermocouple technique. Measurements were obtained intracranially or at the muscle-bone interface using a commercial sector scanner (ATL MK 600, 7.5 MHz scanhead; scan mode, ISPTA) = 27 mW/cm2, ISPPA = 85 W/cm2, pulse repetition frequency (PRF) = 1 kHz; pulsed Doppler - ISPTA = 54 mW/cm2, ISPPA = 1.5 W/cm2, PRF = 18.5 kHz). Overall, the greatest temperature elevation achieved with either modality or location was 0.6 degrees C.     

Experimental hepatitis E: pathogenesis in cynomolgus macaques (Macaca fascicularis)

Children with acute lymphoblastic leukemia (ALL) who have completed 2.5 to 3 years of initial chemotherapy have an off-therapy relapse rate of approximately 20%. In an attempt to improve the survival of children with a late bone marrow (BM) relapse (ie, occurring greater than 6 months after cessation of primary therapy), the Pediatric Oncology Group designed a randomized study to compare the efficacy of doxorubicin/prednisone and cytarabine/teniposide in a multidrug retreatment chemotherapy program. Treatment consisted of remission reinduction with vincristine, prednisone, and doxorubicin, central nervous system prophylaxis with triple intrathecal chemotherapy, and continuation therapy (for 132 weeks) with alternating cycles of oral 6-mercaptopurine/methotrexate and intravenous vincristine/cyclophosphamide. Patients received intermittent courses of either prednisone/doxorubicin (regimen 1) or teniposide/cytarabine (regimen 2) during continuation therapy and a late intensification phase with either vincristine, prednisone, and doxorubicin (regimen 1) or teniposide and cytarabine (regimen 2). One hundred two of 105 evaluable patients (97%) achieved a second complete remission. Twenty-eight of 50 patients on regimen 1 have failed compared with 28 or 52 patients on regimen 2 (log-rank analysis, P = .68), indicating that this trial was inconclusive as to which treatment regimen was superior. The overall 4-year event-free survival for children with a late BM relapse was 37% +/- 6%. Age less than 10 years at initial diagnosis (P < or = .001), white blood cell count less than 5,000/microL at relapse (P = .036) and duration of first remission greater than 54 months (P = .039) were independently associated with a more favorable outcome. While the randomized trial was inconclusive, prolonged second complete remissions were secured in more than one-third of children with a late BM relapse of ALL. The prognostic factors identified may help select children with a late BM relapse who can be successfully retreated with chemotherapy alone.     

Colour cues for leaf food selection by long-tailed macaques (Macaca fascicularis) with a new suggestion for the evolution of trichromatic colour vision

Fast-rate otoacoustic emissions (OAEs) were used to determine the inward and outward transmission change produced by the stapedial muscle reflex. The subjects were otologically normal adult volunteers. Satisfactory recordings were obtained from a total of 16 ears. Runs of 16 click-evoked OAEs were recorded at a rate of 4282 clicks/s using the maximum length sequence (MLS) technique, with a contralateral tone presented at 10 dB above the contralateral acoustic reflex threshold during the recording of OAEs 5-12 in each run. The OAEs recorded with the contralateral tone were compared with those recorded without the tone to determine the effect of the acoustic reflex. An analysis of the OAEs in 0.5 kHz frequency bands suggested that the reflex produced significant attenuation of low frequency sound with smaller effects at high frequencies, which included amplification for some subjects. For eight of the 16 ears there was an increase in OAE amplitude with the acoustic reflex for at least one frequency band. At low frequencies (1, 1.5 kHz) the inward transmission change produced by the acoustic reflex appeared to be similar in magnitude to the outward transmission change.     

Latitudinal and insular variation of skull size in crab-eating macaques (primates, Cercopithecidae: Macaca fascicularis)

Macaca fascicularis is broadly distributed in Southeast Asia across 30 degrees of latitude and 35 degrees of longitude (Indochinese Peninsula, Isthmus of Kra, Malay Peninsula, Greater and Lesser Sunda Islands, Philippine Islands, and numerous small, neighboring islands). The range is divisible into 1) a core area comprised of mainland Southeast Asia, Borneo, Sumatra, and Java (large land masses interconnected during the last glacial maximum, 18,000 B.P.); 2) shallow-water fringing islands, which are smaller islands connected to the core area during the last glacial maximum; and 3) deep-water fringing islands, which are peripheral islands not connected to the core area during the last glacial maximum. Skull length was used to study effects of latitude and insularity on patterns of size variation. The data are from 802 adult M. fascicularis specimens from 140 core-area localities, 63 shallow-water islands, and 29 deep-water islands. Sex-specific polynomial regressions of skull length on latitude were used to describe skull length variation in the core area. These regressions served as standards for evaluating variation among samples from shallow-water and deep-water islands. The core area exhibits Bergmannian latitudinal size clines through most of the species range. Thus, skull length decreases from about 8 degrees S (Java) to the equator (Sumatra and Borneo), then increases as far north as about 13 degrees N (Isthmus of Kra). Farther north, to the northernmost Indochinese localities at about 17 degrees N, skull length in M. fascicularis decreases with increasing latitude, contrary to Bergmann's rule. Latitudinal size variation in shallow-water fringing islands generally parallels that in the core area. However, skull length tends to be smaller than in the core area at similar latitudes. Deep-water fringing islands are markedly more variable, with relatively small specimens in the Lesser Sunda Islands and relatively large specimens in the Nicobar Islands. These analyses illustrate how a primate species may vary in response to latitudinal temperature variation and to isolation.     

Effects of estrogen monotherapy on breast tissue in the primate model (Macaca fascicularis)

Much is unknown about the effects of estrogen's on the mammary gland in postmenopausal women today. In a recent study of estrogenmonotherapy 28 adult, surgically postmenopausal female monkeys (Macaca fascicularis) were treated continuously with estradiol or were given only a diet (control group). After 6 months serum levels of estradiol and progesterone, morphometrical, histopathological and immunohistochemical measurements of the mammary gland were performed. In monkeys receiving estradiol the mammary epithel thickness and the mammary epithelial area (as percentage of total breast area) increased. Estradiol induced mammary gland hyperplasia, but we did not see any atypical hyperplasia. Estradiol and progesterone receptors staining in mammary ducts and lobuli increased (not significant). Estradiol induced a mammary gland proliferation (not significant) shown as increased staining for PCNA and Ki67.     

Ectopic expression of hoxb2 after retinoic acid treatment or mRNA injection: disruption of hindbrain and craniofacial morphogenesis in zebrafish embryos

To investigate pattern formation in the vertebrate hindbrain, we isolated a full length hoxb2 cDNA clone from zebrafish. In a gene phylogeny, zebrafish hoxb2 clusters with human HOXB2, and it maps on linkage group 3 along with several other loci whose orthologues are syntenic with human HOXB2. In the hindbrain, hoxb2 is expressed at high levels in rhombomere 3 (r3), lower levels in r4, still lower in r5, and at undetectable levels in r6. In r7, r8, and the rostral spinal cord, hoxb2 is expressed at a lower level than in r5. Lateral cells appearing to emanate from r4 express both hoxb2 and dlx2, suggesting that they are neural crest. Overexpression of hoxb2 by mRNA injections into early cleavage stage embryos resulted in abnormal morphogenesis of the midbrain and rostral hindbrain, abnormal patterning in r4, fusion of cartilage elements arising from pharyngeal arches 1 and 2, and ectopic expression of krx20 and valentino (but not pax2, rtk1, or hoxb1) in the rostral hindbrain, midbrain, and, surprisingly, the eye. Treatments with retinoic acid produced a phenotype similar to that of ectopic hoxb2 expression, including ectopic krx20 (but not valentino) expression in the eye, and fusion of cartilages from pharyngeal arches 1 and 2. The results suggest that hoxb2 plays an important role in the patterning of hindbrain and pharyngeal arches in the zebrafish.     

Aging, dominance history, and social behavior in Java-monkeys (Macaca fascicularis)

The aim of this study was to investigate the influence of the dominance history of socially housed Java-monkeys on the aging process. In monkeys, social subordinance is generally associated with elevated levels of cortisol, which, in turn, have been suggested to influence cognitive decline. As cognitive skills are necessary for successful social life, we investigated the effect of old age in relation to the dominance history of the animals on their social behavior by comparing old females with their younger daughters. Old age, especially in combination with a history of low rank, led to a withdrawal from social interactions with unfamiliar animals and to a decrease in amounts of aggression received. Still, however, old animals showed an increase in behaviors associated with arousal. A reduced ability to deal with complex social interactions, caused by a decline in information processing abilities, is suggested as an explanation for these results.     

Cyclic changes in genital organs and vaginal cytology in cynomolgus monkeys (Macaca fascicularis)

Vaginal cytology was evaluated weekly over 12 months in 20 adult female Cynomolgus monkeys (Macaca fascicularis). After sacrifice of the animals the histology of the ovaries, uterus and vagina were studied in different phases of the menstrual cycle. The cytological examination of the vaginal smears showed that the superficial cells increased in number towards the middle of the cycle and the number of intermediate cells declined gradually. Parabasal cells were observed mainly at the beginning of the cycle; they disappeared towards the middle of the menstrual cycle. During the early follicular phase, the cells were moderately separated from each other, and during the second half of the proliferative or follicular phase, the superficial cells appeared clumped together. Leucocytes were usually absent except for at the beginning of the cycle and in the last few days of the late secretory or luteal phase. The maturation index of the vaginal smears can be considered as a tool for distinguishing the different phases of the menstrual cycle. The microscopic examination of the genital organs showed that during the proliferative or follicular phase of the cycle, which corresponds to the development of the ovarian follicles, the uterus showed growth of endometrial glands, stroma and endothelial cell proliferation with capillary sprouts. Shortly after ovulation and parallel to the formation of the corpora lutea, the endometrium enters the secretory or luteal phase, which is characterized by coiling of endometrial glands, glandular secretion and the differentiation of the spiral artery. The most striking changes in the vagina, is the marked basal cell proliferation and thickening of the stratum granulosum during the follicular phase of the menstrual cycle. The histological changes observed in the vagina demonstrated a good correlation with the observation on cytological examination of the smears. The present study demonstrated that the process of angiogenesis in the uterus during the different phases of the menstrual cycle is a multiple phenomenon involving proliferation, maturation and differentiation.     

Hiding and perspective taking in long-tailed macaques (Macaca fascicularis).

Seven long-tailed macaques (Macaca fascicularis) were trained by threes not to drink from a juice nipple as long as an experimenter was facing them. However, they were allowed to drink when the experimenter was standing with his or her back turned. During transfer tests, the monkeys had a choice between 2 juice nipples, one uncovered and the other hidden from the experimenter by a wooden screen, while the experimenter was facing them. We tested whether the monkeys would then prefer to drink behind the screen, thus demonstrating that they transferred knowledge acquired during training. Results did not yield a significant outcome, suggesting that the macaques did not transfer the observable "experimenter's visible open eyes" and that they did not take the experimenter's perspective. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fiber type composition of abdominal muscles in Japanese macaques (Macaca fuscata)

The muscle fiber composition and cross-sectional area of muscle fiber types were investigated histochemically in the abdominal muscles (rectus abdominis muscle, obliquus externus abdominis muscle, obliquus internus abdominis muscle and transversus abdominis muscle) of three Japanese macaques (Macaca fuscata). Muscle fibers were classified into three fiber types (Type I, II A and II B) by myosin ATPase activity and succinate dehydrogenase activity. Each abdominal muscle in Japanese macaques contained high proportion of Type II B fibers and there were no large differences in the fiber type composition between the abdominal muscles. The range of mean fiber type percent was 26-32% Type I, 21-22% Type II A, and 46-52% Type II B fibers. Thus, based on the histochemical fiber type composition, the separate abdominal muscles appear to have a similar functional capacity. The cross-sectional area was larger for Type II than for Type I fibers, and the areas were similar in Type II A and Type II B fibers in each muscle. The rectus abdominis showed larger fibers of each type compared to the lateral abdominal muscles. The high proportion of Type II B fibers and large fiber size for Type II B fibers suggest that the abdominal muscles of Japanese macaques have properties similar to the propulsive and locomotory muscles in the limbs.     

Effects of the nonsteroidal aromatase inhibitor, fadrozole, on the sexual behavior of male cynomolgus monkeys (Macaca fascicularis)

In many vertebrates, castration and hormone replacement and, more recently, the use of aromatase inhibitors, have shown that male sexual activity is mediated by the aromatization of testosterone (T) to estradiol (E2). In macaques, however, the systemic administration of E2, either alone or in combination with androgen, failed either to maintain or to restore the sexual activity of castrated males. The present study examines the effects of administering the nonsteroidal aromatase inhibitor, Fadrozole, either alone or combined with E2, to castrated, T-treated male cynomolgus monkeys at a dose of 0.25 mg/kg/day. This dose inhibited by over 98% the conversion of T to E2 and the subsequent accumulation of the latter in hypothalamic cell nuclei. Castrated males bearing sc Silastic impants of T were each tested with an ovariectomized, E2-treated female partner before, during, and after being given minipumps delivering either Fadrozole or water (240 1-hr tests). Within 2 weeks, Fadrozole significantly reduced ejaculatory activity and male sexual motivation in the absence of changes in plasma T levels, which remained in the upper range for intact males. Additional estradiol treatment produced small but significant increases in ejaculations by three of the six males only, and measures of male sexual motivation remained unchanged (120 tests). The present results, which stand in contrast to our previous findings in macaques, support the view that aromatization of T is important for ejaculatory activity and sexual motivation in a male primate. They also suggest that exogenous E2, which reaches the brain from the systemic circulation, does not fully duplicate the behavioral effects of E2 produced locally in the brain by the aromatization of T.     

Fatal disseminated cercopithecine herpesvirus 1 (herpes B infection in cynomolgus monkeys (Macaca fascicularis)

Two adult female cynomolgus monkeys (Macaca fascicularis) that had been housed together for 4 months died within 2 weeks of each other after brief illnesses. Monkey No. 1 presented with collapse, watery stool, and hypothermia and died overnight. Monkey No. 2 presented with dyspnea, nasal discharge, leukopenia, and hypoproteinemia and was euthanized after 2 days. Both animals had peritoneal effusions, massive necrosis of pharyngeal, esophageal, and gastric mucosa, and multifocal hepatic and pancreatic necrosis. Monkey No. 2 also had lingual ulcers and locally extensive necrosis of spleen, adrenal glands, and lymph nodes. Large numbers of eosinophilic intranuclear inclusion bodies were present in epithelial and syncytial cells adjoining the necrotic foci in Monkey No. 2 but were absent in Monkey No. 1. Monkey No. 1 seroconverted to cercopithecine herpesvirus 1 (CHV-1, commonly known as herpes B) in the month before death. CHV-1 was isolated from a sample of stomach from Monkey No. 2, and electron microscopy of liver from this animal demonstrated herpesvirus particles within hepatocytes. Both animals were seropositive for simian type D retrovirus, and the virus was cultured from the liver of Monkey No. 2. A diagnosis of disseminated CHV-1 infection was made, possibly occurring secondary to immunosuppression due to infection with simian type D retrovirus. Although a high percentage of cynomolgus monkeys are apparently infected with CHV-1, disseminated disease is rare. Because infection with CHV-1 in humans is associated with a high fatality rate, familiarity with the lesions of disseminated infection with this virus is important.     

Resistance to psychopathology in adolescent monkeys (Macaca fascicularis) reared with mothers and peers.

Extended S. J. Suomi's (1971) incarceration-separation procedure for the production of depressive behavior pathology to mother- and peer-reared, adolescent Java monkeys (2 males and 2 females) (Macaca fascicularis). In light of recent protein deprivation studies, an attempt to assess the extent of self-inflicted food deprivation was also made. Although there were significant differences in the amount of food consumed, no pathological behavior patterns developed. In general, the experimental manipulations appeared to be associated with increased social interest rather than with depression. Mother-peer-reared adolescents appear to be resistant to experimentally induced psychopathology. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure of carbon monoxide to induce myocardial infarction in cholesterol-fed cynomolgus monkeys (Macaca fascicularis)

The effect of prenatal administration of different doses of cortisone, corticosterone, dexamethasone, triamcinolone and prednisolone on the fetus and its palatal development was studied. All the glucocorticoids, except cortisone, produced cleft palate in the fetuses. Both the total frequency and morphologically different types of cleft palate were related to the dose of the teratogen. Triamcinolone appeared to be more potent than other glucocorticoid in inducing cleft palate. An association was noted between fetal growth inhibition, the dose of the teratogen and the frequency and type of cleft palate.     

13-cis-retinoic acid in silicone-fluorosilicone copolymer oil in a rabbit model of proliferative vitreoretinopathy

The purpose of this study was to evaluate the effect of 13-cis-Retinoic Acid (RA) in Silicone-Fluorosilicone Copolymer Oil (SiFO) in a rabbit model of proliferative vitreoretinopathy (PVR). Rabbits underwent gas-compression vitrectomy. During gas-SiFO exchange, group 1 was injected with 1 ml (10 microg ml-1) 13-cis-RA in SiFO, group 2 with 1.5 ml (9 microg 1.5 ml-1) all-trans-RA in SiFO, group 3 with 1 ml SiFO alone, and group 4 with balanced salt solution (BSS). Groups 1-4 were also injected with 0.1 ml suspension of fibroblasts (75,000 0.1 ml-1) and 0.05 ml platelet rich plasma (70,000 0.1 ml-1), and were observed for 4 weeks. Group 5 was injected with SiFO alone, group 6 with 1 ml (10 microg ml-1) 13-cis-RA in SiFO, group 7 with 1.5 ml (9 microg 1.5 ml-1) all-trans-RA in SiFO, and group 8 with BSS. After 4 weeks, groups 5-7 underwent SiFO-BSS exchange. ERG and histopathology were performed to test for retinal toxicity in groups 5-8. The incidence of traction retinal detachment at 4 weeks was: group 1, 42.9%; group 2, 36.4%; group 3, 87.5%; and group 4, 88.9%. A significant difference in the incidence of PVR was noted between treated eyes (groups 1 and 2) and control eyes (groups 3 and 4) at 2, 3, and 4 weeks (P<0.05). No significant difference in the incidence of PVR was found between groups 1 and 2 during the same observation periods. ERG and histopathological studies showed no differences between the treated and the control fellow eyes (group 5-7) after 4 weeks. 13-cis-RA in SiFO (10 microg ml-1) is as effective as all-trans-RA in SiFO (9 microg 1.5 ml-1) in controlling the incidence of PVR when used for short term retinal tamponade and does not appear to be associated with retinal toxicity.     

Microbiology of ligature-induced marginal inflammation around osseointegrated implants and ankylosed teeth in cynomolgus monkeys (Macaca fascicularis)

The aim of this study was to characterize the changes in the quantitative expression of beta 2-integrins and L-selectin detected by means of fluorochrome-conjugated monoclonal antibodies and flow cytometry on leukocytes in the systemic circulation after a major musculoskeletal trauma, i.e. hip replacement surgery, and to relate these changes to parameters of the acute-phase response [plasma acute-phase reactants (C-reactive protein, CRP, and interleukin-6, IL-6) and parameters of coagulation activation (thrombin-antithrombin III complexes, TAT)]. Eight patients with either primary or secondary osteoarthritis of the hip received uncemented total hip prostheses. LFA-1 (CD11a/CD18) was upregulated on granulocytes during the operation. MAC-1 (CD11b/CD18) expression on monocytes increased to peak levels 20 h after surgery, whereas the L-selectin (CD62L) expression on monocytes and granulocytes reached peak values at the end of surgery. The changes in expression of LFA-1 on monocytes, MAC-1 on granulocytes and p150,95 (CD11c/CD18) on monocytes and granulocytes during and after the operation did not reach statistical significance. TAT and IL-6 increased during surgery and reached peak values at the end of the operation and 20 h after surgery, respectively. In contrast, CPR concentrations increased after surgery with peak levels 44 h postoperatively. Significant upregulation of LFA-1 on granulocytes and L-selectin on monocytes and granulocytes preceded the increase in IL-6 which again preceded the increase in CRP. However, the up- or downregulation of leukocyte beta 2-integrins and L-selectin during and after surgery was not significantly correlated with the increase in IL-6. The increases in TAT correlated well with the upregulation of L-selectin on monocytes, but not with the beta 2-integrins known to participate in the coagulation process in vitro. The rise in CRP was inversely correlated with the maximal increase in expression of MAC-1 on monocytes. In conclusion, the changes in leukocyte adhesion molecules during and after surgery indicate changes in critical leukocyte functions. The lack of correlation between quantitative up- and downregulation of leukocyte beta 2-integrins and parameters of the acute phase response suggests that these processes are regulated through independent pathways or that functional up- and downregulation of adhesion molecules, shedding, leukocyte-endothelial adhesion and mobilization of new unactivated cells may result in a net estimate of leukocyte activation not suspected to be positively correlated to acute-phase reactants.     

Developmental toxicity of fleroxacin and comparative pharmacokinetics of four fluoroquinolones in the cynomolgus macaque (Macaca fascicularis)

The potential developmental toxicity of fleroxacin was studied (Phase I) and its pharmacokinetics was compared to ciprofloxacin, temafloxacin, and norfloxacin (Phase II) in the cynomolgus macaque (Macaca fascicularis). Phase I studies involved oral administration of fleroxacin (35 and 70 mg/kg-day) during Gestational Days (GD) 20-34 or 35-49 (N = 10/group); controls received vehicle only. Increased maternal toxicity (weight loss, anorexia, emesis) and embryolethality (4/10, 40%; GD 20-34) were observed at 70 mg/kg-day. Urinary excretion of estrogen conjugates was reduced for females with nonviable pregnancies during both treatment periods (GD 20-34 and 35-49), although steroid hormone levels in serum remained unchanged during treatment; no malformations or growth retardation were observed at gross examination. For Phase II studies, the pharmacokinetics of fleroxacin (70 mg/kg), ciprofloxacin (100 mg/kg), temafloxacin (100 mg/kg), and norfloxacin (150 mg/kg) were studied during a 3-day oral treatment regimen in the nonpregnant (N = 12; 3/quinolone) and pregnant (N = 3; fleroxacin only) macaque. Serial blood samples were collected on the first and third days of treatment in all animals; for pregnant females, the conceptus was removed on GD 31 for analysis of fleroxacin levels. Marked differences between the quinolones were noted in the AUC0-24 hr for nonpregnant females. Based on AUC0-24 hr on the first day of treatment, the rank order was fleroxacin > temafloxacin > ciprofloxacin > norfloxacin. On the third of treatment, the rank order for exposure was temafloxacin > fleroxacin > ciprofloxacin > norfloxacin. Overall, results indicated (1) no marked differences in pharmacokinetic parameters in pregnant versus nonpregnant females, (2) fleroxacin levels in embryonic tissues were similar to maternal plasma levels, and (3) there was a correlation between exposure and embryolethal doses for all fluoroquinolones which resulted in embryolethality except norfloxacin.     

Comparative assessment of psychomotor performance: target prediction by humans and macaques (Macaca mulatta)

Although nonhuman primates such as rhesus monkeys (Macaca mulatta) have been useful models of many aspects of cognition and performance, it has been argued that, unlike humans, they may lack the capacity to respond as predictor-operators. Data from the present series of experiments undermine this claim, suggesting instead a continuity of predictive competency between humans and nonhuman primates. A prediction coefficient was devised to examine the degree to which each subject's response path approximated the optimal predictive strategy. Whereas human subjects (N = 30) generally predicted more accurately, rhesus monkeys (N = 10) also significantly anticipated the movements of the target in all conditions. It appears that humans and rhesus monkeys both exhibit the capacity to respond to where a stimulus is going.     

Characterization of CYP1A in hepatocytes of cynomolgus monkeys (Macaca fascicularis) and induction by different substituted polychlorinated biphenyls (PCBs)

We have developed a mathematical algorithm to compare and distinguish matrix-assisted laser desorption/ionization (MALDI) mass spectra of whole bacteria cells. This fingerprint matching technique eliminates the subjectivity involved in visually comparing two spectra to determine whether they match and it provides a quantitative measure of spectral similarity. Using it, we have distinguished twenty five different strains of a single bacteria species, E. coli. Cells are grown in culture, samples are prepared, and MALDI-TOF mass spectra are recorded for each strain. Pairs of spectra are compared by a modified cross-correlation procedure. This modified approach increases the sensitivity of correlation analysis to small spectral differences. The technique can be fine-tuned by varying the number of intervals into which spectra are divided.