Identification and Quantification of a Pneumococcal Cell Wall Polysaccharide by Antibody-Enhanced Chromatography Assay.

Multivalent pneumococcal vaccines have been developed successfully to combat invasive pneumococcal diseases (IPD) and reduce the associated healthcare burden. These vaccines employ pneumococcal capsular polysaccharides (PnPs), either conjugated or unconjugated, as antigens to provide serotype-specific protection. Pneumococcal capsular polysaccharides used for vaccine often contain residual levels of cell wall polysaccharides (C-Ps), which can generate a non-serotype specific immune response and complicate the desired serotype-specific immunity. Therefore, the C-P level in a pneumococcal vaccine needs to be controlled in the vaccine process and the anti C-P responses need to be dialed out in clinical assays. Currently, two types of cell-wall polysaccharide structures have been identified: a mono-phosphocholine substituted cell-wall polysaccharide C-Ps1 and a di-phosphocholine substituted C-Ps2 structure. In our effort to develop a next-generation novel pneumococcal conjugate vaccine (PCV), we have generated a monoclonal antibody (mAb) specific to cell-wall polysaccharide C-Ps2 structure. An antibody-enhanced HPLC assay (AE-HPLC) has been established for serotype-specific quantification of pneumococcal polysaccharides in our lab. With the new anti C-Ps2 mAb, we herein extend the AE-HPLC assay to the quantification and identification of C-Ps2 species in pneumococcal polysaccharides used for vaccines.

Placental differences between severe fetal growth restriction and hypertensive disorders of pregnancy requiring early preterm delivery: morphometric analysis of the villous tree supported by artificial intelligence.

BACKGROUND: The great obstetrical syndromes of fetal growth restriction and hypertensive disorders of pregnancy can occur individually or be interrelated. Placental pathologic findings often overlap between these conditions, regardless of whether 1 or both diagnoses are present. Quantification of placental villous structures in each of these settings may identify distinct differences in developmental pathways. OBJECTIVE: This study aimed to determine how the quantity and surface area of placental villi and vessels differ between severe, early-onset fetal growth restriction with absent or reversed umbilical artery Doppler indices and hypertensive disorders of pregnancy or the 2 conditions combined among subjects with disease severity that warrant early preterm delivery. We hypothesized that the trajectories of placental morphogenesis diverge after a common initiating insult of deep defective placentation. Specifically, we postulated that only villi are affected in pregnancy-related hypertension, whereas both villous and vascular structures are proportionally diminished in severe fetal growth restriction with no additional effect when hypertension is concomitantly present. STUDY DESIGN: In this retrospective cohort study, paraffin-embedded placental tissue was obtained from 4 groups, namely (1) patients with severe fetal growth restriction with absent or reversed umbilical artery end-diastolic velocities and hypertensive disorders of pregnancy, (2) patients with severe fetal growth restriction with absent or reversed umbilical artery Doppler indices and no hypertension, (3) gestational age-matched, appropriately grown pregnancies with hypertensive disease, and (4) gestational age-matched, appropriately grown pregnancies without hypertension. Dual immunohistochemistry for cytokeratin-7 (trophoblast) and CD34 (endothelial cells) was performed, followed by artificial intelligence-driven morphometric analyses. The number of villi, total villous area, number of fetoplacental vessels, and total vascular area across villi within a uniform region of interest were quantified. Quantitative analyses of placental structures were modeled using linear regression. RESULTS: Placentas from pregnancies complicated by hypertensive disorders of pregnancy exhibited significantly fewer stem villi (-282 stem villi; 95% confidence interval, -467 to -98; P<.01), a smaller stem villous area (-4.3 mm2; 95% confidence interval, -7.3 to -1.2; P<.01), and fewer stem villous vessels (-4967 stem villous vessels; 95% confidence interval, -8501 to -1433; P<.01) with no difference in the total vascular area. In contrast, placental abnormalities in cases with severe growth restriction were limited to terminal villi with global decreases in the number of villi (-873 terminal villi; 95% confidence interval, -1501 to -246; P<.01), the villous area (-1.5 mm2; 95% confidence interval, -2.7 to -0.4; P<.01), the number of blood vessels (-5165 terminal villous vessels; 95% confidence interval, -8201 to -2128; P<.01), and the vascular area (-0.6 mm2; 95% confidence interval, -1.1 to -0.1; P=.02). The combination of hypertension and growth restriction had no additional effect beyond the individual impact of each state. CONCLUSION: Pregnancies complicated by hypertensive disorders of pregnancy exhibited defects in the stem villi only, whereas placental abnormalities in severely growth restricted pregnancies with absent or reversed umbilical artery end-diastolic velocities were limited to the terminal villi. There were no significant statistical interactions in the combination of growth restriction and hypertension, suggesting that distinct pathophysiological pathways downstream of the initial insult of defective placentation are involved in each entity and do not synergize to lead to more severe pathologic consequences. Delineating mechanisms that underly the divergence in placental development after a common inciting event of defective deep placentation may shed light on new targets for prevention or treatment.

An intravenous pancreatic cancer therapeutic: Characterization of CRISPR/Cas9n-modified Clostridium novyi-Non Toxic.

Clostridium novyi has demonstrated selective efficacy against solid tumors largely due to the microenvironment contained within dense tumor cores. The core of a solid tumor is typically hypoxic, acidic, and necrotic-impeding the penetration of current therapeutics. C. novyi is attracted to the tumor microenvironment and once there, can both lyse and proliferate while simultaneously re-activating the suppressed immune system. C. novyi systemic toxicity is easily mitigated by knocking out the phage DNA plasmid encoded alpha toxin resulting in C. novyi-NT; but, after intravenous injection spores are quickly cleared by phagocytosis before accomplishing significant tumor localization. C. novyi-NT could be designed to accomplish intravenous delivery with the potential to target all solid tumors and their metastases in a single dose. This study characterizes CRISPR/Cas9 modified C. novyi-NT to insert the gene for RGD, a tumor targeting peptide, expressed within the promoter region of a spore coat protein. Expression of the RGD peptide on the outer spore coat of C. novyi-NT indicates an increased capacity for tumor localization of C. novyi upon intravenous introduction based on the natural binding of RGD with the αvß3 integrin commonly overexpressed on the epithelial tissue surrounding a tumor, and lead to immune stimulation.

Inflammatory Myofibroblastic Tumor of the Larynx: Report of a Case.

PURPOSE: Inflammatory myofibroblastic tumor (IMT) is a rare tumor composed of mesenchymal myofibroblastic spindle cells enveloped by an inflammatory infiltrate. Historically, this tumor sparked debate regarding whether it was a true malignancy with metastatic potential or merely a locally destructive physiologic inflammatory response. Few reports of IMT exist in the recent literature, with the majority of cases occurring in the pediatric population and favoring the lungs. Here we present an exceedingly rare case of IMT involving the larynx of a 22-year-old female. RESULTS: A hemorrhagic and solid mass of the right true membranous vocal fold was excised and sent for histopathological assessment. Features of the surgical specimens were diagnostic for IMT. Intralesional steroid therapy was selected for additional treatment. Panendoscopy facilitated surveillance for any additional or recurrent lesions, of which there were none. At 11 months post-excision, follow-up MRI revealed symmetric vocal cords without evidence of any masses. CONCLUSIONS: Although rare, laryngeal IMT should be considered in any patient presenting with hoarseness due to a vocal fold mass. Based on the successful treatment of our patient, we suggest that our approach of surgical excision followed by intralesional corticosteroid injection may be an efficacious treatment approach for this rare tumor. However, more research is warranted to elucidate the most effective, safe, and cost-effective treatment approach.

One-Step Regio- and Stereoselective Electrochemical Synthesis of Orexin Receptor Antagonist Oxidative Metabolites.

Synthesis of drug metabolites, which often have complex structures, is an integral step in the evaluation of drug candidate metabolism, pharmacokinetic (PK) properties, and safety profiles. Frequently, such synthetic endeavors entail arduous, multiple-step de novo synthetic routes. Herein, we present the one-step Shono-type electrochemical synthesis of milligrams of chiral α-hydroxyl amide metabolites of two orexin receptor antagonists, MK-8133 and MK-6096, as revealed by a small-scale (pico- to nano-mole level) reaction screening using a lab-built online electrochemistry (EC)/mass spectrometry (MS) (EC/MS) platform. The electrochemical oxidation of MK-8133 and MK-6096 was conducted in aqueous media and found to produce the corresponding α-piperidinols with exclusive regio- and stereoselectivity, as confirmed by high-resolution nuclear magnetic resonance (NMR) characterization of products. Based on density functional theory (DFT) calculations, the exceptional regio- and stereoselectivity for this electrochemical oxidation are governed by more favorable energetics of the transition state, leading to the preferred secondary carbon radical α to the amide group and subsequent steric hindrance associated with the U-shaped conformation of the cation derived from the secondary α-carbon radical, respectively.

Bacterial Involvement in Progression and Metastasis of Adenocarcinoma of the Stomach.

Gastric cancer metastasis is a process in which the tumor microenvironment may carry significant influence. Helicobacter pylori (H. pylori) infection is well-established as a contributor to gastric carcinoma. However, the role that these bacteria and others may play in gastric carcinoma metastasis is a current focus of study. A review of the literature was conducted to elucidate the process by which gastric adenocarcinoma metastasizes, including its ability to utilize both the lymphatic system and the venous system to disseminate. Studies that investigate the tumor microenvironment at both the primary and secondary sites were assessed in detail. H. pylori and Mycoplasma hyorhinis (M. hyorhinis) were found to be important drivers of the pathogenesis of gastric adenocarcinoma by modifying various steps in cell metastasis, including epithelial-mesenchymal transition, cell migration, and cell invasion. H. pylori is also a known driver of MALT lymphoma, which is often reversible simply with the eradication of infection. M. hyorhinis has been implicated in gastric neoplasia via ß-catenin stabilization and subsequent activation of the WNT-signaling pathway, promoting gastric cancer cell motility and inciting cancer progression. Fusobacterium nucleatum (F. nucleatum) and its association with worse prognosis in diffuse-type gastric adenocarcinoma are also reviewed. Recognition of the roles that bacteria play within the metastatic cascade is vital in gastrointestinal adenocarcinoma treatment and potential reoccurrence. Further investigation is needed to establish potential treatment for metastatic gastric carcinoma by targeting the tumor microenvironment.

Bacterial Involvement in Progression and Metastasis of Colorectal Neoplasia.

While the gut microbiome is composed of numerous bacteria, specific bacteria within the gut may play a significant role in carcinogenesis, progression, and metastasis of colorectal carcinoma (CRC). Certain microbial species are known to be associated with specific cancers; however, the interrelationship between bacteria and metastasis is still enigmatic. Mounting evidence suggests that bacteria participate in cancer organotropism during solid tumor metastasis. A critical review of the literature was conducted to better characterize what is known about bacteria populating a distant site and whether a tumor depends upon the same microenvironment during or after metastasis. The processes of carcinogenesis, tumor growth and metastatic spread in the setting of bacterial infection were examined in detail. The literature was scrutinized to discover the role of the lymphatic and venous systems in tumor metastasis and how microbes affect these processes. Some bacteria have a potent ability to enhance epithelial-mesenchymal transition, a critical step in the metastatic cascade. Bacteria also can modify the microenvironment and the local immune profile at a metastatic site. Early targeted antibiotic therapy should be further investigated as a measure to prevent metastatic spread in the setting of bacterial infection.

Potential Therapeutic Targets for Combination Antibody Therapy against Pseudomonas aeruginosa Infections.

Despite advances in antimicrobial therapy and even the advent of some effective vaccines, Pseudomonas aeruginosa (P. aeruginosa) remains a significant cause of infectious disease, primarily due to antibiotic resistance. Although P. aeruginosa is commonly treatable with readily available therapeutics, these therapies are not always efficacious, particularly for certain classes of patients (e.g., cystic fibrosis (CF)) and for drug-resistant strains. Multi-drug resistant P. aeruginosa infections are listed on both the CDC's and WHO's list of serious worldwide threats. This increasing emergence of drug resistance and prevalence of P. aeruginosa highlights the need to identify new therapeutic strategies. Combinations of monoclonal antibodies against different targets and epitopes have demonstrated synergistic efficacy with each other as well as in combination with antimicrobial agents typically used to treat these infections. Such a strategy has reduced the ability of infectious agents to develop resistance. This manuscript details the development of potential therapeutic targets for polyclonal antibody therapies to combat the emergence of multidrug-resistant P. aeruginosa infections. In particular, potential drug targets for combinational immunotherapy against P. aeruginosa are identified to combat current and future drug resistance.

A cohort study of personal and family history of skin cancer in relation to all-cause and cancer-specific mortality.

PURPOSE: Even though the fatality rate from skin cancers is low, evidence from a few cohort studies has raised the possibility that people with a personal history of skin cancer may have a higher all-cause mortality rate compared with those without a personal history of skin cancer. The purpose of the present study was to investigate the potential links between a personal history or family history of skin cancer and all-cause and cancer-specific mortality METHODS: A prospective cohort (n = 8,622) was assembled within the NHANES I follow-up study. Cox Proportional Hazard Regression analysis was used to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for the association for personal and family history of skin cancer and all-cause and cancer-specific mortality. RESULTS: After adjustment for several potential confounding variables, a personal history of skin cancer was associated with decreased risk for all-cause mortality (HR 0.72, 95% CI 0.61-0.85), whereas the results for cancer-specific mortality were consistent with a null association (HR 0.97, 95% CI 0.74-1.27). A family history of skin cancer was not significantly associated with all-cause mortality (HR 0.97, 95% CI 0.76-1.24) or cancer-specific mortality (HR 0.69, 95% CI 0.38-1.24). CONCLUSION: The results of the present study do not support the hypothesis that a personal history or family history of skin cancer is associated with an increased risk of all-cause or cancer-specific mortality. The high prevalence of skin cancer adds to the public health significance of this question, providing a strong rationale for further research to resolve this question.

Probing the Molecular-Level Interactions in an Active Pharmaceutical Ingredient (API) - Polymer Dispersion and the Resulting Impact on Drug Product Formulation.

PURPOSE: An investigation of underlying mechanisms of API-polymer interaction patterns has the potential to provide valuable insights for selecting appropriate formulations with superior physical stability and processability. MATERIALS AND METHODS: In this study, copovidone was used as a polymeric carrier for several model compounds including clotrimazole, nifedipine, and posaconazole. The varied chemical structures conferred the ability for the model compounds to form distinct interactions with copovidone. Rheology and nuclear magnetic resonance (NMR) were combined to investigate the molecular pattern and relative strength of active pharmaceutical ingredient (API)-polymer interactions. In addition, the impact of the interactions on formulation processability via hot melt extrusion (HME) and physical stability were evaluated. RESULTS: The rheological response of an API-polymer system was found to be highly sensitive to API-polymer interaction, depending both on API chemistry and API-polymer miscibility. In the systems studied, dispersed API induced a stronger plasticizer effect on the polymer matrix compared to crystalline/aggregated API. Correspondingly, the processing torque via HME showed a proportional relationship with the maximum complex viscosity of the API-polymer system. In order to quantitatively evaluate the relative strength of the API-polymer interaction, homogeneously dispersed API-polymer amorphous samples were prepared by HME at an elevated temperature. DSC, XRD, and rheology were employed to confirm the amorphous integrity and homogeneity of the resultant extrudates. Subsequently, the homogeneously dispersed API-polymer amorphous dispersions were interrogated by rheology and NMR to provide a qualitative and quantitative assessment of the nature of the API-polymer interaction, both macroscopically and microscopically. Rheological master curves of frequency sweeps of the extrudates exhibited a strong dependence on the API chemistry and revealed a rank ordering of the relative strength of API-copovidone interactions, in the order of posaconazole > nifedipine > clotrimazole. NMR data provided the means to precisely map the API-polymer interaction pattern and identify the specific sites of interaction from a molecular perspective. Finally, the impact of API-polymer interactions on the physical stability of the resultant extrudates was studied. CONCLUSION: Qualitative and quantitative evaluation of the relative strength of the API-polymer interaction was successfully accomplished by utilizing combined rheology and NMR. Graphical Abstract.

Keratinocyte Carcinoma and Risk for Another Type of Cancer: Assessment of a Dose-response Relationship.

BACKGROUND/AIM: Keratinocyte carcinoma (KC) is a marker of increased risk of other cancer types. To assess if this association exhibits a dose-response relationship, a case-control study was carried out. PATIENTS AND METHODS: This was a clinic-based study of cases with KC plus another type of cancer matched by age, race (all Caucasian), sex and histologic type to controls with KC only (n=48 matched pairs). RESULTS: Compared with the KC only group, those with KC plus another cancer had a mean number of lesions that were 43%, 35%, and 41% greater for basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and total KC, respectively. The odds ratio (OR) of developing another type of cancer increased from 1.0 to 1.09 (95% confidence interval (CI)=0.23-5.13) to 2.12 (95%CI=0.50-9.08) according to whether the patient had zero, one, or ≥two BCC lesions; for SCC, the corresponding ORs were 1.0, 1.24 (95%CI=0.48-3.24), and 1.39 (95%CI=0.29-6.61). CONCLUSION: A dose-response relationship seems to exist between the number of skin lesions and the risk of another type of cancer, but the lack of statistical significance weakens this evidence.

A cohort study of personal and family history of skin cancer in relation to future risk of non-cutaneous malignancies.

PURPOSE: Skin cancer has repeatedly been observed to be a marker of increased risk for developing an internal malignancy. The purpose of our study was to further investigate this association while also characterizing the potential role of family history of skin cancer in relation to risk for non-cutaneous malignancies. METHODS: Our study used data from 8,408 participants from the NHANES I epidemiological follow-up study. Cox-proportional hazards models were used to estimate the risk for developing an internal cancer associated with a personal history and family history of skin cancer during follow-up. RESULTS: A personal history of skin cancer was associated with significantly increased risk of developing an internal cancer in adjusted models [hazard ratio (HR) 1.33, 95% confidence interval (CI) 1.09-1.61] but a family history of skin cancer was not associated with increased risk (HR 0.80, 95% CI 0.58-1.11). CONCLUSIONS: Consistent with prior reports, a personal history of skin cancer was associated with increase of developing internal malignancies, but this did not hold true for a family history of skin cancer. Further research is needed to understand why a personal history of skin cancer acts as a marker for increased risk for internal cancer.

Real-time fluorescence imaging for visualization and drug uptake prediction during drug delivery by thermosensitive liposomes.

Objective: Thermosensitive liposomal doxorubicin (TSL-Dox) is a promising stimuli-responsive nanoparticle drug delivery system that rapidly releases the contained drug in response to hyperthermia (HT) (>40 °C). Combined with localized heating, TSL-Dox allows highly localized delivery. The goals of this study were to demonstrate that real-time fluorescence imaging can visualize drug uptake during delivery, and can predict tumor drug uptake. Methods: Nude mice carrying subcutaneous tumors (Lewis lung carcinoma) were anesthetized and injected with TSL-Dox (5 mg/kg dose). Localized HT was induced by heating tumors for 15, 30 or 60 min via a custom-designed HT probe placed superficially at the tumor location. In vivo fluorescence imaging (excitation 523 nm, emission 610 nm) was performed before, during, and for 5 min following HT. After imaging, tumors were extracted, drug uptake was quantified by high-performance liquid chromatography, and correlated with in vivo fluorescence. Plasma samples were obtained before and after HT to measure TSL-Dox pharmacokinetics. Results: Local drug uptake could be visualized in real-time during HT. Compared to unheated control tumors, fluorescence of heated tumors increased by 4.6-fold (15 min HT), 9.3-fold (30 min HT), and 13.2-fold (60 min HT). HT duration predicted tumor drug uptake (p = .02), with tumor drug concentrations of 4.2 ± 1.3 µg/g (no HT), 7.1 ± 5.9 µg/g (15 min HT), 14.1 ± 6.7 µg/g (30 min HT) and 21.4 ± 12.6 µg/g (60 min HT). There was good correlation (R2 = 0.67) between fluorescence of the tumor region and tumor drug uptake. Conclusions: Real-time in vivo fluorescence imaging can visualize drug uptake during delivery, and can predict tumor drug uptake.

How broadly can poly(urethane)-based implants be applied to drugs of varied properties?

Implants offer the opportunity to improve patient adherence and real-world outcomes. However, most polymers used today are hydrophobic and limit drug properties suitable for development. Thermoplastic poly(urethanes) (TPUs) form pores upon hydration and may facilitate the development of implants containing drugs exhibiting broadly different properties. We sought to investigate the effect of drug physicochemical properties on permeability through membranes of varying TPU mixture composition; leverage imaging to visualize microstructural changes to the membrane across the TPU mixture composition range; and quantitatively characterize the membrane microstructure using equivalent pore analysis. We observed a correlation between drug hydrophobicity and its permeability through hydrophobic-rich TPU membranes. Conversely, all compounds diffused through hydrophilic-rich TPU membranes at similar rates, regardless of drug properties. Imaging revealed significant microstructure differences between hydrophobic-rich and hydrophilic-rich TPU membranes, supporting hypotheses proposed in our previous study. The hydrated hydrophilic TPU membrane pore area was determined to be 0.583% and its equivalent pore radius was found to be 128 nm, suggesting that hydrophilic TPU membranes may be used to modify the release of small molecular weight drugs and macromolecules. These findings highlight the benefits of hydrophilic TPUs as rate-controlling membranes to modulate the release rate of drugs with varying physicochemical properties.

Microbial biotransformation - an important tool for the study of drug metabolism.

Metabolite identification is an integral part of both preclinical and clinical drug discovery and development. Synthesis of drug metabolites is often required to support definitive identification, preclinical safety studies and clinical trials. Here we describe the use of microbial biotransformation as a tool to produce drug metabolites, complementing traditional chemical synthesis and other biosynthetic methods such as hepatocytes, liver microsomes and recombinant human drug metabolizing enzymes. A workflow is discussed whereby microbial strains are initially screened for their ability to form the putative metabolites of interest, followed by a scale-up to afford quantities sufficient to perform definitive identification and further studies. Examples of the microbial synthesis of several difficult-to-synthesize hydroxylated metabolites and three difficult-to-synthesize glucuronidated metabolites are described, and the use of microbial biotransformation in drug discovery and development is discussed.

Enrichment of Relevant Oxidative Degradation Products in Pharmaceuticals With Targeted Chemoselective Oxidation.

The ability to produce and isolate relatively pure amounts of relevant degradation products is key to several aspects of drug product development: (a) aid in the unambiguous structural identification of such degradation products, fulfilling regulatory requirements to develop safe formulations (International Conference on Harmonization Q3B and M7); (b) pursue as appropriate safety evaluations with such material, such as chronic toxicology or Ames testing; (c) for a specified degradation product in a late-stage regulatory filing, use pure and well-characterized material as the analytical standard. Producing such materials is often a resource- and time-intensive activity, either relying on the isolation of slowly formed degradation products from stressed drug product or by re-purposing the drug substance synthetic route. This problem is exacerbated if the material of interest is an oxidative degradation product, because typical oxidative stressing (H2O2 and radical initiators) tends to produce a myriad of irrelevant species beyond a certain stress threshold, greatly complicating attempts for isolating the relevant degradation product. In this article, we present reagents and methods that may allow the rapid and selective enrichment of active pharmaceutical ingredient with the desired oxidative degradation product, which can then be isolated and used for purposes described above.

Synthesis and Antiviral Evaluation of Carbocyclic Nucleoside Analogs of Nucleoside Reverse Transcriptase Translocation Inhibitor MK-8591 (4'-Ethynyl-2-fluoro-2'-deoxyadenosine).

MK-8591 (4'-ethynyl-2-fluoro-2'-deoxyadenosine) is a novel nucleoside analog that displays a differentiated mechanism of action as a nucleoside reverse transcriptase translocation inhibitor (NRTTI) compared to approved NRTIs. Herein, we describe our recent efforts to explore the impact of structural changes to the properties of MK-8591 through the synthesis and antiviral evaluation of carbocyclic derivatives. Synthesized analogs were evaluated for their antiviral activity, and the corresponding triphosphates were synthesized and evaluated in a biochemical assay. 4'-Ethynyl-G derivative (±)-29 displayed a promising IC50 of 33 nM in a hPBMC cell-based antiviral assay, and its triphosphate (TP), (±)-29-TP, displayed an IC50 of 324 nM in a biochemical RT-polymerase assay. Improved TP anabolite delivery resulting in improved in vitro potency was achieved by preparing the corresponding phosphoramidate prodrug of single enantiomer 29b, with 6-ethoxy G derivative 34b displaying a significantly improved IC50 of 3.0 nM, paving the way for new directions for this novel class of nucleoside analogs.

Observed Effectiveness of Palivizumab for 29-36-Week Gestation Infants.

BACKGROUND: Respiratory syncytial virus (RSV) is a common reason for hospitalization of infants. In clinical trials, palivizumab reduced RSV hospitalization rates for premature infants. The 2014 American Academy of Pediatrics clinical practice guideline advised against use of palivizumab for otherwise healthy infants ≥29 weeks' gestation. The aim of this study was to determine the effect of palivizumab administration on hospitalization rates for RSV and bronchiolitis without RSV diagnosis among infants 29 to 36 weeks' gestation who do not have chronic illness. METHODS: Claims data were extracted from databases of 9 Texas Medicaid managed care programs. Eligible infants were 29 to 36 weeks' gestation, without claims suggesting chronic illness, and who were born between April 1 and December 31 of 2012, 2013, and 2014. RESULTS: A total of 2031 eligible infants of 29 to 32 weeks' gestation and 12 066 infants of 33 to 36 weeks' gestation were identified; 41.5% of the infants 29 to 32 weeks' gestation and 3.7% of the infants 33 to 36 weeks' gestation had paid claims for dispensing of ≥1 palivizumab doses. Among the infants of 29 to 32 weeks' gestation, palivizumab dispensing was associated with reduced RSV hospitalization rates (3.1% vs 5.0%, P = .04) but increased hospitalizations for bronchiolitis without RSV diagnosis (3.3% vs 1.9%, P = .05). There were no significant differences by palivizumab administration status for the infants of 33 to 36 weeks' gestation. CONCLUSIONS: Among infants 29 to 32 weeks' gestation without chronic illness, palivizumab use was associated with reduced RSV hospitalizations but increased hospitalizations for bronchiolitis without RSV diagnosis.