[Tumor Mechanomedicine].

Malignant tumors represent a significant health challenge, critically impacting human well-being. Historically, the focus has been on leveraging the biochemical cues of tumors for both diagnosis and treatment. While valuable, this strategy does not capture the full complexity of tumor diagnosis and management. Recently, the integration of biomechanics and mechanobiology with oncology has highlighted the importance of mechanical cues, which have emerged as new hallmarks of tumors, opening potential novel routes for cancer diagnosis and therapeutic interventions. Despite the advances, a thorough literature review suggests a pronounced gap in our understanding of the mechanical properties of tumors. The clinical community has not yet completely recognized the diagnostic and therapeutic relevance of the mechanical cues of tumors. To bridge this knowledge gap, we propose and introduce the paradigm of "Tumor Mechanomedicine". We provide a comprehensive overview of the multi-scale mechanical characteristics of tumors, exploring their influence on tumor biology, from the aspects of tumor biomechanics, tumor mechanobiology, tumor mechanodiagnostics, and tumor mechanotherapeutics. By elucidating the diagnostic and therapeutic potential of these mechanical cues, we aim to furnish the oncology community with fresh insights, paving the way for innovative solutions to persistent clinical conundrums.

[Microanatomy and functional MRI study of arcuate fasciculus and superior longitudinal fasciculus].

Objectives: To explore the microanatomy and functional MRI(fMRI) of arcuate fasciculus(AF) and superior longitudinal fasciculus(SLF),and to analyze their functions. Methods: Ten normal adult cadaveric head specimens (20 cerebral hemispheres) were fixed with 10% methanal at the Translational Research Institute for Neurological Disorders of the Wannan Medical Collegefrom February to December 2022.The Klingler fiber dissection technique was utilized to perform white matter fiber dissection,with a magnification ranging from 6 to 40.The study focused on the microanatomical structures of the AF and SLF,aiming to explore their relationships with deep brain fibers.Furthermore, six healthy adult volunteers who underwent fMRI of the brain were included.The collected diffusion tensor imaging (DTI) data were processed and integrated with the microanatomical findings for a comprehensive analysis. Results: After removing the gray matter of the cerebral cortex,the superficial U fibers were exposed.The long association fibers that beneath the U fibers were the AF and SLF,which were the main long association fibers in the superficial layers of the brain.The AF could be divided into dorsal and ventral parts,while the SLF could be divided into Ⅰ,Ⅱ,and Ⅲ.SLF Ⅰ lied within the upper bank of the cingulate sulcus,travels medial to the callosal sulcus.The SLF Ⅱ,Ⅲ,and the AF were located on the lateral surface of the brain.By removing the gray matter of the insular cortex and the extreme capsule,exposing the external capsule and claustrum.Subsequently,the AF and SLF Ⅱ,Ⅲ were dissected,revealing the corona radiata and sagittal stratum,along with other deep brain fibers.During the dissection,it was observed that there was a close connection between the AF,SLF Ⅱ,and the deep brain fibers.Furthermore,in the regions above the lateral fissure of the cerebral hemisphere,there was no direct connection of long association fibers between the gray matter cortex and the deep U fibers in the coronal plane.These findings were further supported by DTI studies. Conclusions: The AF and SLF are the major long association fibers that located in the superficial layers of the brain,and closely connect to the gray matter cortex and U fibers,even closely relate with deep brain fibers.In the regions above the lateral fissure of the hemisphere,only the AF and SLF Ⅱ and Ⅲ serve as superficial long association fibers in the anterior-posterior direction.These fibers are likely involved in the transmission of brain functional information between the top and bottom gray matter cortex in the coronal plane above the lateral fissure.

Nomograms for predicting survival in patients with gastric carcinoid or neuroendocrine carcinoma based on the SEER database.

OBJECTIVE: The aim of this study was to construct a competent model that can effectively predict the prognosis of patients with gastric carcinoid (GC) or neuroendocrine carcinoma (NEC). PATIENTS AND METHODS: Data of patients with GC or NEC were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database from 1975 to 2017. Univariable and multivariable Cox analysis was used to determine the independent factors for patients with GC or NEC. Nomograms were established based on the independent factors and the results were evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). RESULTS: A total of 214 patients with GC and 65 patients with gastric NEC were extracted from the SEER database. Independent prognostic factors for patients with GC were M stage, gender, age, and chemotherapy. Independent prognostic factors for patients with gastric NEC included age, M stage, and chemotherapy. ROC curves, calibration curves, and DCA confirmed that the nomograms can precisely predict the prognosis of patients with GC and NEC. CONCLUSIONS: The nomograms can effectively predict survival in patients with GC or NEC, which may assist the clinician in their decision-making and quantitatively judge the prognosis of individual patients.

Association between early vasopressor administration and in-hospital mortality in critically ill patients with acute pancreatitis: A cohort study from the MIMIC-IV database.

OBJECTIVE: This study aims to explore the association between early administration of vasopressors and in-hospital mortality in acute pancreatitis (AP) patients admitted to the ICU. PATIENTS AND METHODS: The MIMIC-IV database was used to identify AP patients who had and had not received vasopressors. Univariate and multivariate logistic regression, propensity score matching (PSM), and inverse probability of treatment weighting (IPTW) were used for statistical analysis. RESULTS: A total of 894 AP patients admitted to the ICU were included in the study. Among them, AP patients who received vasopressors were associated with an increased risk of in-hospital mortality in the unadjusted model (OR: 7.77, 95% CI 4.92-12.61, p<0.001), multivariable-adjusted model (OR: 2.51,95% CI 1.1-5.76, p<0.05), PSM model (OR: 2.58, 95% CI 1.03-6.85, p<0.05) and IPTW model (OR: 1.82, 95% CI 1.06-3.15, p<0.05) compared with patients who did not receive vasopressors. In the subgroup analysis, age (≥ 65 years old: OR: 2.5, 95% CI 0.82-7.91; <65 years old: OR: 4.63, 95% CI 0.84-26.41), male (OR: 1.19, 95% CI 0.35-4.03), ethnicity (white: OR: 2.49, 95% CI 0.81-7.62; non-white: OR: 4.28, 95% CI 0.85-23.7), usage of norepinephrine (OR: 2.29, 95% CI 0.91-5.78), and single-use of vasopressor (OR: 1.48, 95% CI 0.43-4.95) were not associated with in-hospital mortality in patients with AP, whereas vasopressin (OR: 4.27, 95% CI 1.24-15.13; p<0.05) and phenylephrine usage (OR: 4.75, 95% CI 1.66-13.95; p<0.05), combined vasopressor usage (OR: 4.41, 95% CI 1.55-12.96; p<0.01), and female usage (OR: 7.89, 95% CI 2.03-34.2; p<0.01) were associated with in-hospital mortality. CONCLUSIONS: Early vasopressor use is significantly associated with increased in-hospital mortality among critically ill AP patients. This association might be greater in females, vasopressin, phenylephrine, and combined vasopressor users. Our results may benefit clinicians as they can guide the rational use of vasopressors in critically ill AP patients admitted to the ICU.

[Epidemic situation and diagnosis of imported malaria before and after malaria elimination in Nanjing City, Jiangsu Province].

OBJECTIVE: To analyze the epidemiological characteristics and diagnosis of imported malaria before and after malaria elimination in Nanjing City of Jiangsu Province, so as to provide the scientific evidence for formulating the malaria control strategy after malaria elimination. METHODS: Data pertaining to the epidemic situation and individual investigation of malaria in Nanjing City before (from 2012 to 2016) and after malaria elimination (from 2017 to 2020) were captured from the National Notifiable Communicable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention and were analyzed statistically. RESULTS: A total of 178 malaria cases were reported in Nanjing City from 2012 to 2020, and all were imported cases. There were 99 malaria cases reported before malaria elimination in Nanjing City, including 78 cases with Plasmodium falciparum malaria (78.79%), 5 cases with P. vivax malaria (5.05%), 10 cases with P. ovale malaria (10.10%), 3 cases with P. malariae malaria (3.03%) and 3 cases with mixed infections (3.03%), and 79 malaria cases reported after elimination, including 63 cases with P. falciparum malaria (79.75%), 5 cases with P. vivax malaria (6.33%), 9 cases with P. ovale malaria (11.39%), 2 cases with P. malariae malaria (2.53%). There was no significant difference in the proportion of each type of malaria cases in Nanjing City before and after malaria elimination (χ2 =2.400, P > 0.05). Malaria cases mainly acquired Plasmodium infections in African regions, and no significant difference was seen in the proportion of malaria cases returning to Nanjing City from African countries before and after malaria elimination (χ2 = 0.093, P > 0.05). The number of malaria cases peaked in Nanjing City in January and during the period from May to July before elimination, and there was no apparent seasonal variation in the distribution of malaria cases after elimination. The proportion of malaria cases living in Nanjing City was significantly greater after malaria elimination than before elimination (72.15% vs. 55.56%; χ2 = 5.187, P = 0.023). The proportions of businessmen and international students were both 5.05% before malaria elimination, and increased to 15.19% and 13.92% after elimination, respectively (χ2 = 5.229 and 4.229, both P values < 0.05). The percentage of definitive diagnosis of malaria at initial diagnosis was 18.75% in county-level hospitals before malaria elimination and increased to 61.11% after elimination (χ2 = 6.275, P = 0.012), while the proportion of malaria cases with definitive diagnoses in county-level hospitals was 4.04% before malaria elimination and increased to 13.92% after elimination (χ2 = 5.562, P = 0.018). During the period from 2012 to 2020, the proportion of malaria cases with definitive diagnoses within 1 to 3 days post-admission increased from 27.27% in Nanjing City before malaria elimination to 45.57% after elimination (χ2 = 6.433, P = 0.011). CONCLUSIONS: The epidemic situation of imported malaria remains serious in Nanjing City during the post-elimination stage, and malaria parasite infections predominantly occur in African regions. In addition, there are changes in regional and occupational distributions of malaria cases and the diagnostic capability of malaria increases in county-level hospitals in Nanjing City after malaria elimination. Further improvements in the malaria surveillance system and the diagnostic and treatment capability of malaria in medical institutions at each level are required to consolidate malaria elimination achievements in Nanjing City.

[Effect of integrated schistosomiasis control measures on Oncomelania snails in river channels connecting the Yangtze River in Nanjing City].

OBJECTIVE: To evaluate the effectiveness of Oncomelania snails control following the implementation of integrated schistosomiasis control measures in river channels connecting the Yangtze River in endemic areas of Nanjing City. METHODS: The river channels connecting the Yangtze River with snails in Nanjing City were selected as the study pilots. The integrated schistosomiasis control measures implemented in the study pilots were investigated by means of retrospective analyses and field surveys from 1998 to 2019, and the effectiveness of snail control was evaluated. RESULTS: Integrated control measures with emphases on environmental improvements including water resource projects for schistosomiasis control were implemented in the study pilots during the period from 1998 to 2019, including river bank concretion with 84.51 km in length, marshland cutting and dredging with 50.41 km in length, building 2 sluices and 3 overflow dams, digging one floodway and snail control with chemical treatment that covered an area of 3 370.80 hm2. No Schistosoma japonicum infection had been detected in snails since the completion of the integrated control measures. In addition, snails had been eliminated in 6 river channels connecting the Yangtze River until 2019, with the snail habitats reducing from 214.33 hm2 to 52.22 hm2 in 10 river channels connecting the Yangtze River and the snail density reducing to below 0.1 snails/0.1 m2 in snail-breeding river channels connecting the Yangtze River. CONCLUSIONS: The integrated schistosomiasis control measures with emphases on environmental improvements may effectively control snail breeding and spread in rivers connecting the Yangtze River in endemic areas of schistosomiasis; however, the maintenance of the project and snail surveillance and control should be intensified following the completion of the integrated schistosomiasis control measures.

Expression of maspin in invasive fungal rhinosinusitis.

OBJECTIVE: This study aimed to test the expression of maspin in invasive fungal rhinosinusitis and explore its value in diagnosing invasive fungal rhinosinusitis. METHODS: Forty-two fungal rhinosinusitis cases (12 invasive and 30 non-invasive) were selected as the experimental group, and 30 chronic rhinosinusitis cases comprised the control group. Maspin expression was assessed in nasal mucous membrane specimens by immunohistochemical staining. RESULTS: Compared with the control group, maspin expression was down-regulated in the fungal rhinosinusitis group (p < 0.05). Furthermore, the staining score for maspin was lowest in the invasive fungal rhinosinusitis group, as compared with both the non-invasive fungal rhinosinusitis group and the control group (p < 0.05). A maspin staining score of 5.70 was the critical value for diagnosis of invasive fungal rhinosinusitis, with sensitivity and specificity of 91.7 per cent and 88.3 per cent, respectively. CONCLUSION: The results of this study suggest that the maspin staining score may be a biomarker for effective and rapid diagnosis of invasive fungal rhinosinusitis.

[Report and analysis of 2 cases of nerve paralysis with aspiration pneumonia after infection of herpes zoster virus].

Two cases of patients were hospitalized for sore throat with Dysphagia.Check:Wall of the pharynx,tongue and epiglottis scattered the ulcer.The patients were loss of pharynx reflex.Oropharynx and piriform fossa has a lot of saliva retention.Posterior pharyngeal wall was drooping like waterfull.CT scan showed may be the aspiration pneumonia in right lower lung.The admission diagnosiswere pharyngeal herpes zoster virus infection,pharyngeal side muscle paralysis,and inhalation pneumonia.The patients' clinical data were retrospectively analyzed,and the report is as follows.

First Report of Gray Mold of Rhizoma paridis Caused by Botrytis cinerea in China.

Rhizoma paridis is a perennial, traditional Chinese medicinal herb. In May 2013, a disease was observed in an approximately 10 ha cultivated field in Enshi, Hubei Province, China. Approximately 80% of plants in the field were affected. Symptoms were visible on the basal leaves of affected plants. Chlorosis followed by necrosis started at the leaf tips and margins and gradually spread inward until the entire leaf was necrotic. Thick, gray mycelium and conidia were visible on both sides surface of leaves under wet, humid conditions. The leading edge of the chlorotic leaves was excised from 20 plant samples surface disinfested with 1% NaOCl solution for 1 min, rinsed in sterile water, air dried, and placed on potato dextrose agar (PDA). Plates were incubated at 22°C in the dark. Mycelia were initially hyaline and white, and became dark gray after 72 h. Mycelia were septate with dark branched conidiophores. Conidia were smooth, hyaline, ovoid, aseptate, and ranged from 8 to 14.5 × 7 to 8.5 µm. Numerous hard, small, irregular, and black sclerotia that were 1 to 3 × 2 to 5 mm were visible on PDA plates after 12 days. The fungus was identified as Botrytis cinerea on the basis of these characters (1). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1 and ITS4 primer and sequenced (GenBank Accession No. KF265499). BLAST analysis of the PCR product showed 99% identity to Botryotinia fuckeliana (perfect stage of B. cinerea) (EF207415.1, EF207414.1). The pathogen was further identified to the species level as B. cinerea using gene sequences from glyceraldehyde-3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) (2) (KJ638600, KJ638602, and KJ638601). Pathogenicity was tested by spraying the foliage of 40 two-year-old plants with a suspension of 106 conidia per ml of sterile distilled water. Each plant received 30 ml of the inoculum. Ten healthy potted plants were inoculated with sterilized water as control. All plants were covered with plastic bags for 5 days after inoculation to maintain high relative humidity and were placed in a growth chamber at 22°C. The first foliar lesions developed on leaves 7 days after inoculation and were similar to those observed in the field. No symptoms developed on the control plants. B. cinerea was consistently re-isolated from all artificially inoculated plants. The pathogenicity test was completed twice. To our knowledge, this is the first report of gray mold of R. paridis caused by B. cinerea in China. The root of R. paridis is the most commonly used Chinese herbal medicine to treat viper bites. In recent years, cultivation of this herb has increased in China because of its high value. Consequently, the economic importance of this disease is likely to increase with the greater prevalence of this host species. References: (1) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972. (2) M. Staats et al. Mol. Biol. Evol. 22:333, 2005.

The human cytomegalovirus UL97 protein is a protein kinase that autophosphorylates on serines and threonines.

The product of the human cytomegalovirus (CMV) UL97 gene, which controls ganciclovir phosphorylation in virus-infected cells, is homologous to known protein kinases but diverges from them at a number of positions that are functionally important. To investigate UL97, we raised an antibody against it and overexpressed it in baculovirus-infected insect cells. Recombinant baculovirus expressing full-length UL97 directed the phosphorylation of ganciclovir in insect cells, which was abolished by a four-codon deletion that confers ganciclovir resistance to CMV. When incubated with [gamma-32P]ATP, full-length UL97 was phosphorylated on serine and threonine residues. Phosphorylation was severely impaired by a point mutation that alters lysine-355 in a motif that aligns with subdomain II of protein kinases. However, phosphorylation was impaired much less severely by the four-codon deletion. A UL97 fusion protein expressed from recombinant baculovirus was purified to near homogeneity. It too was phosphorylated upon incubation with [gamma-32P]ATP in vitro. This phosphorylation, which was abolished by the lysine 355 mutation, was optimal at high NaCl and high pH. The activity required either Mn2+ or Mg2+, with a preference for Mn2+, and utilized either ATP or GTP as a phosphate donor, with Kms of 2 and 4 microM, respectively. The phosphorylation rate was first order with protein concentration, consistent with autophosphorylation. These data strongly argue that UL97 is a serine/threonine protein kinase that autophosphorylates and suggest that the four-codon deletion affects its substrate specificity.

[Exploration of nursing diagnosis with a cognitive reasoning model].

One of the important topics in theoretic studies on nursing diagnosis, still a new concept in China, is to explore the logical reasoning process from collecting data to making diagnoses. This paper introduced an epistemological model which mentions every step in detail on how to make a nursing diagnosis. The model was built on the basis of analyzing the knowledge structure of nursing diagnosis and applying the methodology of cognitive psychology.

An M13 phage library displaying random 38-amino-acid peptides as a source of novel sequences with affinity to selected targets.

We have examined the potential of isolating novel ligands from a library of M13 pIII-fusion phage displaying peptides composed of 38 random amino acids (aa). The library was panned with streptavidin (SA) and a polyclonal goat antimouse IgG Fc antibody (Ab) preparation coupled to paramagnetic beads. SA selected two classes of phage from the library. One class exhibited the aa motif, HP(Q/M) theta (where theta signifies a non-polar aa), similar to the motif identified by Devlin et al. [Science 249 (1990) 404-406] using a 15-aa random peptide library displayed on phage. The other class of phage had no discernible motif. In binding experiments, the non-HP(Q/M) theta phage had a slightly higher affinity for SA than did the motif phage. Both classes of SA-binding phage failed to bind native and non-glycosylated forms of avidin, even though SA and avidin are structurally similar and both proteins possess extraordinary affinities for biotin. The polyclonal goat anti-mouse IgG Fc Ab preparation selected phage displaying sequences similar to a region of the mouse IgG Fc. Thus, a single immunodominant epitope on the mouse IgG Fc was identified. Furthermore, a second phage displaying peptides with no discernible sequence similarities to mouse IgG Fc was isolated. Thus, an M13 library displaying 38-aa peptides can yield phage with affinity for various targets. Finally, we have observed a biological bias against odd numbers of Cys residues in the displayed peptides.

[The stereoselectivity of chrono-pharmacokinetic parameters of hydratropic acid in rats].

The stereoselective chrono-pharmacokinetic parameters of hydratropic acid in rats were studied. The results showed that under standard light-dark cycle pharmacokinetic parameters of T1/2 alpha and CL are stereoselective and under reverse light-dark cycle, parameters T1/2 beta, AUC, CL, Vc and MRT were shown to be stereoselective. To compare the corresponding parameters of the two different light-dark cycles using t-test, no differences were found in most of them.

[Stereoselective chronopharmacokinetics of hydratropic acid in rats].

The circadian rhythms of hydratropic acid (HTA) pharmacokinetic parameters were studied by using consinor method. Under standard light-dark cycle, the T1/2 beta and CL of S(+)-HTA, T1/2 beta of R(-)-HTA and CL, MRT of RS (+/-)-HTA were found to have circadian rhythm. Circadian rhythms were also found in the T1/2 beta and AUC of S (+)-HTA, CLS of R(-)-HTA and RS(+/-)-HTA under reverse light--dark cycle. Stereoselective circadian rhythms were found in CL of S(+)-HTA under standard light-dark cycle and in T1/2 beta and AUC of S(+)-HTA and CL of R(-)-HTA under reverse light-dark cycle. After ip administration of RS(+/-)-HTA to rat under two different light-dark cycles, the peak phases of circadian rhythms in the biotransformation of R(-)-HTA to S(+)-HTA in rat were both at the end of the dark phase. This suggests that administration of the drug at early morning is a recommendable scheme for chronotherapy with HTA.

Characterization of human cytomegalovirus UL84 early gene and identification of its putative protein product.

The DNA sequence and transcription pattern of human cytomegalovirus early gene UL84 were analyzed. This gene was mapped within a 2.6-kb PstI fragment located between 0.534 and 0.545 map unit of the large unique segment of the human cytomegalovirus genome, which is adjacent to the pp65 and pp71 genes. A 2.0-kb mRNA was transcribed from this region in the same leftward direction as the mRNAs of the pp65 and pp71 genes. The message was first detected at 2.5 h postinfection and reached a maximal level between 72 and 96 h postinfection. The nucleotide sequences of the 2.6-kb PstI genomic DNA fragment and the cDNA derived from this region were determined. The resulting data revealed a polyadenylation signal (AATAAA) located 14 nucleotides upstream from the poly(A) tail of the cDNA and a 1,761-bp open reading frame capable of encoding a 65-kDa polypeptide. A potential leucine zipper was found in the N-terminal half of the peptide molecule between amino acids 114 and 135. In addition, a different periodic leucine repeat with leucine at every eighth position was found between amino acids 325 and 373. The transcriptional initiation site of this early gene was determined by primer extension analysis. A putative TATA box (TATTTAA) located 24 bp upstream of the cap site and several inverted repeats were found in the region further upstream of the TATA box. To test whether the open reading frame of this cDNA encodes a virus-specific protein, the cDNA was overexpressed in Escherichia coli as a fusion protein used to generate antibodies in rabbits. A protein with a molecular size of 65 kDa was detected in the infected-cell extracts harvested at 6 to 72 h postinfection, but not in purified virions, using immunoblot analysis. Both nuclear and cytoplasmic fluorescences were found at late stages of virus infection. From the results obtained, we postulate that UL84 may be a stable, virus-specific, nonstructural protein capable of forming a homo- or heterodimeric molecule.

Cloning of GL-7-ACA acylase gene from Pseudomonas sp. 130 and its expression in Escherichia coli.

Using BamHI digested and dephosphorylated pBR322 as vector, a GL-7-ACA acylase gene from Pseudomonas sp. 130 chromosomal DNA was cloned and expressed in Escherichia coli C600. Seven positive clones were detected from 3205 recombinant plasmids with 32P-labeled oligonucleotide probes in situ hybridization. Out of them, three clones which produced active GL-7-ACA acylase were identified by radio-immunological assay, chemical test and chromatographic analysis of reaction mixture. The plasmid DNAs of recombinant pMR5, pMR6 and pMR7 were extracted. Analysis of gel electrophoresis indicated that pMR5 and pMR7 contained the same 6.8kb fragment and the size of the insert in pNR6 was 5.7 kb. The effects of various E. coli hosts on the expression of cloned GL-7-ACA acylase gene is also presented.

Preparation of high purity IgG and its application in screening for clones positive for Vibrio succinogenes L-asparaginase gene.

A previous paper reported application of L-asparaginase IgG from Vibrio succinogenes in screening for positive clones. This paper describes the detailed procedure for preparation of high-purity IgG, an essential step of which involves coupling of a cell-free extract of host E. coli Y 1090 to Sepharose 4B beads and adsorption of the non-specific antigen components by passage of the polyvalent IgG through this affinity column. The IgG thus obtained exhibited improved specificity and was utilized as a radioimmunologic and horseradish peroxidase-linked immunologic probe in screening for positive clones. These IgG probes had the advantages of low background, high sensitivity, and good reliability.

Dextran sulfate as an inhibitor against the human immunodeficiency virus.

Dextran sulfate (DS) is a potent inhibitor of the growth of human immunodeficiency virus type 1 (HIV-1) in the H9 cell. Its minimal inhibitory concentration is about 1 microgram/ml. Its therapeutic index is greater than or equal to 200 which is higher than that of 38 for zidovudine. At the ID100 range, DS blocks the synthesis of HIV-1 antigens completely for at least 21 days; zidovudine at the subtoxic concentration of 3 micrograms/ml is incapable of achieving such a complete blockage. DS is still active when added to H9 cell cultures 4 hr after the addition of HIV-1. DS does not inactivate extracellular HIV-1 and is incapable of inducing interferons. It interferes partially with the infection of the H9 cells by the HIV-1. It inhibits the activity of HIV-1 reverse transcriptase. These activities may account, at least in part, for the inhibitory activity of dextran sulfate against the HIV-1. DS has a narrow antiviral spectrum; it is noninhibitory to the herpes simplex, vesicular stomatitis, polio, or adeno viruses. Dextran is not inhibitory to HIV-1. After sulfonation, the sulfonated dextran is highly inhibitory. Therefore, the sulfate group in the DS molecule appears to be essential for its anti-HIV-1 activity. The molecular weights of DS within the range 4000 to 12,000 do not appear to influence its anti-HIV potency.