Synthesis of heterocycle-modified betulinic acid derivatives as antitumor agents

A series of novel heterocycle-modified betulinic acid (BA) derivatives were synthesized and investigated for their activity against the growth of eight non-drug resistant and one multidrug-resistant tumor cell line using a sulforhodamine B (SRB) assay. The most active compound 17 showed an average IC50 1.19 μM, which was about 20 times more potent than the lead compound BA. It is amazing that for most synthetic saturated N-heterocycle derivatives, MCF-7/ADR was the most sensitive tumor cells, especially 17 showed the most potent antitumor activity (IC50 = 0.33 μM) on this multidrug-resistant tumor cell line, that was 117 times more potent than BA. Most of the tested compounds displayed less toxic on human fibroblasts (HAF) in comparison with the tumor cell lines. The cytometry and transwell migration assays were used to test the ability of 17 to induce apoptosis and inhibit metastasis on tumor cell lines respectively.

Synthesis of novel heterocyclic ring-fused 18β-glycyrrhetinic acid derivatives with antitumor and antimetastatic activity

Glycyrrhetinic acid (GA) is one of the most important triterpenoic acids shows many pharmacological effects, especially antitumor activity. GA triggers apoptosis in various tumor cell lines. However, the antitumor activity of GA is weak, thus the synthesis of new synthetic analogs with enhanced potency is needed. By introducing various five-member fused heterocyclic rings at C-2 and C-3 positions, 18 novel GA derivatives were obtained. These compounds were evaluated for their inhibitory activity against the growth of eight different tumor cell lines using a SRB assay. The most active compound 37 showed IC50 between 5.19 and 11.72 μm, which was about 11-fold more potent than the lead compound GA. An apoptotic effect of GA and 37 was determined using flow cytometry and trypan blue exclusion assays. We also demonstrated here for the first time that GA and the synthetic derivatives exhibited inhibitory effect on migration of the tested tumor cells, especially 37 which was about 20-fold more potent than GA on antimetastatic activity.

Selective formation of six-membered oxa- and carbocycles by the In(III)-activated ring closure of acetylenic substrates

Fifteen examples are disclosed of efficient In(III)-catalyzed six-membered ring closure leading to bi-, tri-, and tetracyclic products.

Inhibition of SREBP by a small molecule, betulin, improves hyperlipidemia and insulin resistance and reduces atherosclerotic plaques

Sterol regulatory element-binding proteins (SREBPs) are major transcription factors activating the expression of genes involved in biosynthesis of cholesterol, fatty acid and triglyceride. In this study, we identified a small molecule, betulin, that specifically inhibited the maturation of SREBP by inducing interaction of SREBP cleavage activating protein (SCAP) and Insig. Inhibition of SREBP by betulin decreased the biosynthesis of cholesterol and fatty acid. In vivo, betulin ameliorated diet-induced obesity, decreased the lipid contents in serum and tissues, and increased insulin sensitivity. Furthermore, betulin reduced the size and improved the stability of atherosclerotic plaques. Our study demonstrates that inhibition SREBP pathway can be employed as a therapeutic strategy to treat metabolic diseases including type II diabetes and atherosclerosis. Betulin, which is abundant in birch bark, could be a leading compound for development of drugs for hyperlipidemia.

Synthesis and biological evaluation of heterocyclic ring-substituted maslinic acid derivatives as novel inhibitors of protein tyrosine phosphatase 1B

A series of maslinic acid derivatives have been synthesized by introducing various fused heterocyclic rings at C-2 and C-3 positions. Their inhibitory effects on PTP1B, TCPTP and related PTPs are evaluated. Most of the compounds exhibited a dramatic increase in inhibitory potency and selectivity, the two most potent PTP1B inhibitors 20 (IC(50)=0.61 microM) and 29 (IC(50)=0.64 microM) showed about 10-fold more potent than lead compound maslinic acid. More importantly, 29 possesses the best selectivity of 6.9-fold for PTP1B over TCPTP.

Design and synthesis of a biotin-tagged photoaffinity probe of paeoniflorin

A trifunctional probe (binding element-photoreactive group-affinity tag) of natural product paeoniflorin was designed and synthesized based on the previous primary structure-activity relationship. This new probe is a potential tool for labeling, purification, and identification of the target proteins.

Critical evaluation of neurolaryngological disorders

Otolaryngological examinations, videostroboscopic image analysis, and laryngeal electromyography were used as a test battery for a critical evaluation in 80 patients. Vocal fold movements were categorized into mobility, restricted mobility, immobility with different positions, and overactive movement. Laryngeal electromyographic examinations were conducted in all patients, and the results were classified into normal, neuropathic, and myopathic patterns. The electromyographic data were integrated with videostroboscopic findings, interpreted with knowledge of biomechanical and electrophysiological mechanisms of the larynx, and correlated clinically with underlying diseases. It is suggested that neurolaryngological procedures are most clinically useful when dictated by a decision-making algorithm.

Laryngeal reflexomyographic responses in rabbits: a neurolaryngological study of glottal movement

The role of the laryngeal reflex in glottal movement has been reported, but its mechanism remains unclear. To further investigate the neurophysiological characteristics of glottal movement, we recorded the laryngeal reflexomyographic responses (LRMRs) to electrical stimulation of the superior laryngeal nerve (SLN) in rabbits. The procedure involved simultaneous recording of the LRMRs from the thyroarytenoid muscles by means of bipolar hooked wire electrodes after electrical stimulation to the SLN. The results demonstrated characteristic patterns of the responses, consisting of R1 and R2, similar to those found in humans. The R1 response was obtained with a latency of 10.7 +/- 0.78 ms. The ipsilateral R2 response was obtained with a latency of 43.76 +/- 4.67 ms in all rabbits, and the contralateral R2 response with a latency from 42.6 to 50.2 ms in 4 rabbits. It was concluded that LRMRs may serve as a potential central laryngeal function test in the investigation of glottal movement control.

Critical evaluation of deafness

OBJECTIVE

The purpose of this study is to investigate the clinical aspects of profound hearing loss (PHL) and their significance for defining deafness.

METHODS

The audiological data were reviewed from 3660 patients who were evaluated in the Otolaryngology Clinic at Louisiana State University in Shreveport, LA, over a 5-year period. The medical charts from the patients were also reviewed for the information of medical diagnosis, surgical records and radiological findings.

RESULTS

There were 34 patients identified with bilateral PHL or deaf, 177 patients with unilateral PHL and 123 patients with borderline PHL. Congenital hearing loss and unknown-cause hearing loss in this series were predominant with 267 cases (79.9%). A surgical management was indicated in 39 cases (11.7%) including middle ear infection, ossicular chain abnormalities and auditory nerve/brainstem tumors.

CONCLUSION

This study suggests that audiometrically PHL should be thoroughly evaluated to detect reversible or remediable conditions by surgical and medical approaches. The diagnosis of deafness should be confirmed by an integration of the audiological data and medical documents including surgical and radiological findings. Aural rehabilitation program should be designed for deaf patients with varied etiology and degree of residual peripheral hearing sensitivity following medical clearance.

Neurotologic evaluation of facial nerve paralysis caused by gunshot wounds

Facial nerve injury is one of the most common neurotologic sequelae of a gunshot wound (GSW) to the head or neck. However, few neurotologic studies have been performed on the nature and time course of such facial nerve impairments. This study was designed to characterize the neurotologic manifestations and time course of facial nerve paralysis caused by GSWs to the head and neck. We conducted a battery of electrodiagnostic tests on 10 patients who had experienced traumatic facial paralysis due to a GSW to the head or neck. The etiologies of facial nerve paralysis--including direct injury, compression, fracture, and concussion of the temporal bone--were demonstrated by audiologic, radiologic, and surgical findings. Hearing loss and other cranial nerve injuries were also seen. Six of the 10 patients experienced a complete paralysis of the facial nerve and a poor recovery of its function. We also present a comprehensive case report on 1 patient as a means of discussing the evaluation of facial nerve function during the course of management.

Clinical interpretations of transient otoacoustic emissions

PURPOSE

The purpose of this study was to characterize the relation of different ordinal patterns of transient otoacoustic emissions (TEOAES) with respect to underlying otologic disorders and auditory status.

PATIENTS AND METHODS

The results of TEOAEs in 225 patients with various auditory disorders were investigated and compared with normative data established from 90 subjects of various ages. TEOAEs were categorized according to four patterns: (1) normal (general response level within 90% of normative data, (2) reduced amplitude (general response level was > or =2 dB peak sound pressure level (pSPL), but less than the mean -1.64 SD of the normative data), (3) abnormal morphology of frequency spectrum (general response level was within normal limits, but reduced at > or =2 individual octave frequencies between 1,000 and 5,000 Hz), and (4) total absence (response level <2 dB pSPL).

RESULTS

This study showed that the normal pattern of TEOAEs, in terms of response amplitude, varied with age. Our results further indicated that a reduced amplitude pattern of TEOAEs was noted in patients with a mild sensorineural hearing loss (SNHL), negative tympanometric pressure, a pressure-equalization tube, and Meniere's disease. TEOAEs provided good frequency-specific information for patients with a noise-induced hearing loss. All patients with ossicular chain abnormalities, more than moderate SNHL, and a middle ear mass or effusion had total absence of TEOAEs. Patients with acoustic neuroma and brainstem lesions presented a complex profile of TEOAEs. In the follow-up of auditory function in patients undergoing otologic surgery, different patterns of TEOAEs between the preoperative and postoperative recordings were evident, which correlated with the hearing thresholds and middle ear status. The abnormal findings of TEOAEs due to specific auditory diseases were discussed.

CONCLUSION

The interpretation of TEOAEs can be facilitated through an analysis of specific patterns and in combination with other audiologic tests.

Current evaluation of pseudohypacusis: strategies and classification

Some cases of pseudohypacusis may involve medicolegal aspects and require a confirmed and quantitative diagnosis. These challenging cases must be identified, and then evaluated with basic audiologic and sophisticated electrophysiologic tests. Data on 64 patients with pseudohypacusis collected over a 4-year period are reported. A classification system was developed from an analysis of these cases and is presented for clinical evaluation and diagnosis. In many cases, conventional audiologic evaluation involving pure tone and speech audiometry may be adequate and sufficient for diagnosis. In more complex cases, evoked otoacoustic emissions (EOAEs) and auditory brain stem responses (ABRs) are needed for confirmation of peripheral auditory sensitivity. We found that EOAEs were the most rapid economical, and objective method, and confirmed the diagnosis of hearing loss in 78.1% of cases. Fifteen percent of subjects required ABRs to substantiate the diagnosis. The reliability of basic audiologic tests based on previous clinical investigations and data from the literature are discussed. We conclude that a thorough knowledge and understanding of pseudohypacusis is essential to verify the existence of pseudohypacusis, to determine its type, and to quantify the auditory thresholds.

Characterization of acoustic reflex latency in normal-hearing subjects

Acoustic reflex latency (ARL) has been suggested as an indicator in otoneurological diagnosis. However, limited normative data are available. Conflicting evidence exists regarding the effect of stimulus parameters such as frequency on ARL. In addition, there has been little research investigating the effects of ipsilateral and contralateral stimulation on ARL. In view of these problems, ARL was measured in 30 normal-hearing subjects using 500, 1000, 2000, 4000 Hz tones, low-pass noise, high-pass noise, broadband noise and clicks as activating stimuli. Six parameters of ARL: 10%-on latency, 90%-on latency, 10%-off latency, 90%-off latency, rise time and fall time, were recorded using computerized equipment and analyzed in correlation to the activating frequency and intensity. This study indicated that 500 Hz, 1000 Hz tones, and band noise were more effective in eliciting measurable ARL, whereas 4000 Hz tone and click produced a low percentage of measurable ARL. ARL was shown to increase as the stimulus frequency increased and stimulus intensity decreased. No statistically significant differences were found between the ipsilateral ARL and contralateral ARL.

Audiologic manifestations of Noonan syndrome

A comprehensive audiologic study of a family with Noonan syndrome is reported together with a review of 20 cases of this syndrome with regard to hearing sensitivity and middle ear status. An incidence of progressive sensorineural hearing loss at the high frequencies is found for 50% of the ears. It is emphasized that early audiologic management may improve the quality of life for patients with Noonan syndrome.

Audiologic Manifestations of Noonan Syndrome

A comprehensive audiologic study of a family with Noonan syndrome is reported together with a review of 20 cases of this syndrome with regard to hearing sensitivity and middle ear status. An incidence of progressive sensorineural hearing loss at the high frequencies is found for 50% of the ears. It is emphasized that early audiologic management may improve the quality of life for patients with Noonan syndrome.

Laryngeal evoked brainstem responses in humans: a preliminary study

Laryngeal evoked brainstem responses (LBRs) were recorded in normal human subjects in an attempt to develop a central laryngeal function test and enhance our understanding of neurolaryngologic disorders. The results showed that the human LBR consists of five positive peaks and five negative peaks reproducible within 10 ms after a vibratory stimulation to the superior laryngeal nerve (SLN). The waveform reproducibility was verified by blocking the SLN and topically anesthetizing the hypopharyngeal cavity. The morphology and latency of peak 5 were similar to results obtained in animal LBR experiments. It was concluded that a vibratory stimulation to the SLN was a noninvasive method to elicit far-field potentials from the central laryngeal pathway. These findings encourage further effort to establish normative data and explore clinical correlations.