Indigofera cryptantha-induced pigmenturia in cattle in South Africa

Two field cases of reddish-black pigmenturia occurred where cattle grazed on an established Cenchrus ciliaris (blue buffalo grass) pasture in South Africa. The pasture was noticeably invaded by Indigofera cryptantha, which was heavily grazed. Apart from the discolored urine, no other clinical abnormalities were detected. Urinalysis revealed hemoglobinuria, proteinuria and an alkaline pH. When the animals were immediately removed from the infested pasture, they made an uneventful recovery. However, a bull died when one of the herds could not be removed from the I. cryptantha-infested pasture. Macroscopically, the kidneys were dark red in color and the urinary bladder contained the dark pigmented urine. Microscopically, the renal tubules contained eosinophilic, granular pigment casts in the lumen. In addition, many renal tubular epithelial cells were attenuated with granular cytoplasm and were detached from the basement membranes. Chemical analysis was performed on dried, milled plant material and two urine samples collected during the field investigations. Qualitative UPLC-UV-qTOF/MS analysis revealed the presence of indican (indoxyl-β-glucoside) in the stems, leaves and pods of I. cryptantha and indoxyl sulfate was identified, and confirmed with an analytical standard, in the urine samples. It is proposed that following ingestion of I. cryptantha, indican will be hydrolysed in the liver to indoxyl and conjugated with sulfate. Indoxyl sulfate will then be excreted in relatively high concentrations in the urine. In the alkaline urine, two indoxyl molecules might dimerize to form leucoindigo with subsequent oxidation to indigo, thus, contributing to the dark pigmentation of the urine. It is also possible that indoxyl sulfate contributed to the renal failure and death of the bull. Although I. suffruticosa-induced hemoglobinuria has been described in Brazil, this is the first report of I. cryptantha-induced pigmenturia in cattle in South Africa.

Corrigendum: An in vitro study to elucidate the effects of Product Nkabinde on immune response in peripheral blood mononuclear cells of healthy donors

[This corrects the article DOI: 10.3389/fphar.2024.1308913.].

An in vitro study to elucidate the effects of product Nkabinde on immune response in peripheral blood mononuclear cells of healthy donors

Introduction: A significant number of the South African population still rely on traditional medicines (TM) as their primary healthcare due to their belief in their holistic healing and immune-boosting properties. However, little to no scientific data is available on the effects of most TM products on cytokine and cellular biomarkers of the immune response. Here, we evaluated the impact of traditional medicine [Product Nkabinde (PN)] in inducing cellular and cytokine biomarkers of inflammation in peripheral blood mononuclear cells (PBMCs) from eight healthy volunteers. Methods: PN was supplied by a local Traditional Health Practitioner (THP). The IC50 (half maximum concentration) of the standardized extract on isolated PBMCs was established using the cell viability assay over 24 h of incubation. Luminex and flow cytometry assays were used to measure cytokine and cellular levels in PBMCs stimulated with PN and/or PHA over 24, 48, and 72 h, respectively. Results: The IC50 concentration of PN in treated PBMCs was established at 325.3 μg/mL. In the cellular activation assay, the percentages of CD38-HLA-DR + on total CD4+ T cells were significantly increased in PBMCs stimulated with PN compared to unstimulated controls after 24 h (p = 0.008). PN significantly induced the production of anti-inflammatory IL-10 (p = 0.041); proinflammatory cytokines IL-1α (p = 0.003), TNF-α (p < 0.0001); and chemokine MIP-1β (p = 0.046) compared to the unstimulated control after 24 h. At 48 h incubation, the production of proinflammatory cytokines IL-1α (p = 0.034) and TNF-α (p = 0.011) were significantly induced following treatment with PN. Conclusion: We conclude that the PN possesses in vitro immunomodulatory properties that may influence immune and inflammatory responses. More studies using PN are needed to further understand key parameters mediating induction, expression, and regulation of the immune response in the context of pathogen-associated infections.

Prioritised identification of structural classes of natural products from higher plants in the expedition of antimalarial drug discovery

The emergence and spread of drug-recalcitrant Plasmodium falciparum parasites threaten to reverse the gains made in the fight against malaria. Urgent measures need to be taken to curb this impending challenge. The higher plant-derived sesquiterpene, quinoline alkaloids, and naphthoquinone natural product classes of compounds have previously served as phenomenal chemical scaffolds from which integral antimalarial drugs were developed. Historical successes serve as an inspiration for the continued investigation of plant-derived natural products compounds in search of novel molecular templates from which new antimalarial drugs could be developed. The aim of this study was to identify potential chemical scaffolds for malaria drug discovery following analysis of historical data on phytochemicals screened in vitro against P. falciparum. To identify these novel scaffolds, we queried an in-house manually curated database of plant-derived natural product compounds and their in vitro biological data. Natural products were assigned to different structural classes using NPClassifier. To identify the most promising chemical scaffolds, we then correlated natural compound class with bioactivity and other data, namely (i) potency, (ii) resistance index, (iii) selectivity index and (iv) physicochemical properties. We used an unbiased scoring system to rank the different natural product classes based on the assessment of their bioactivity data. From this analysis we identified the top-ranked natural product pathway as the alkaloids. The top three ranked super classes identified were (i) pseudoalkaloids, (ii) naphthalenes and (iii) tyrosine alkaloids and the top five ranked classes (i) quassinoids (of super class triterpenoids), (ii) steroidal alkaloids (of super class pseudoalkaloids) (iii) cycloeudesmane sesquiterpenoids (of super class triterpenoids) (iv) isoquinoline alkaloids (of super class tyrosine alkaloids) and (v) naphthoquinones (of super class naphthalenes). Launched chemical space of these identified classes of compounds was, by and large, distinct from that of 'legacy' antimalarial drugs. Our study was able to identify chemical scaffolds with acceptable biological properties that are structurally different from current and previously used antimalarial drugs. These molecules have the potential to be developed into new antimalarial drugs.

Leveraging off higher plant phylogenetic insights for antiplasmodial drug discovery

The antimalarial drug-resistance conundrum which threatens to reverse the great strides taken to curb the malaria scourge warrants an urgent need to find novel chemical scaffolds to serve as templates for the development of new antimalarial drugs. Plants represent a viable alternative source for the discovery of unique potential antiplasmodial chemical scaffolds. To expedite the discovery of new antiplasmodial compounds from plants, the aim of this study was to use phylogenetic analysis to identify higher plant orders and families that can be rationally prioritised for antimalarial drug discovery. We queried the PubMed database for publications documenting antiplasmodial properties of natural compounds isolated from higher plants. Thereafter, we manually collated compounds reported along with plant species of origin and relevant pharmacological data. We systematically assigned antiplasmodial-associated plant species into recognised families and orders, and then computed the resistance index, selectivity index and physicochemical properties of the compounds from each taxonomic group. Correlating the generated phylogenetic trees and the biological data of each clade allowed for the identification of 3 'hot' plant orders and families. The top 3 ranked plant orders were the (i) Caryophyllales, (ii) Buxales, and (iii) Chloranthales. The top 3 ranked plant families were the (i) Ancistrocladaceae, (ii) Simaroubaceae, and (iii) Buxaceae. The highly active natural compounds (IC50 ≤ 1 µM) isolated from these plant orders and families are structurally unique to the 'legacy' antimalarial drugs. Our study was able to identify the most prolific taxa at order and family rank that we propose be prioritised in the search for potent, safe and drug-like antimalarial molecules.

In vitro dual activity of Aloe marlothii roots and its chemical constituents against Plasmodium falciparum asexual and sexual stage parasites

ETHNOPHARMACOLOGICAL RELEVANCE

Aloe marlothii A.Berger (Xanthorrhoeaceae) is indigenous to southern African countries where its aqueous preparations are used in traditional medicine to treat several ailments including hypertension, respiratory infections, venereal diseases, chest pain, sore throat and malaria.

AIM OF THE STUDY

The aims of this study were as follows: (i) isolate and identify the antiplasmodial active compounds in A. marlothii roots. As the water extract was previously inactive, the dichloromethane:methanol (DCM:MeOH) (1:1) was used, (ii) examine the activity of the isolated compounds against Plasmodium falciparum asexual blood stage (ABS) parasites as well as for transmission-blocking activity against gametocytes and gametes, and (iii) to use in silico tools to predict the target(s) of the active molecules.

MATERIALS AND METHODS

The crude DCM:MeOH (1:1) extract of A. marlothii roots was fractionated on a reverse phase C8 column, using a positive pressure solid-phase extraction (ppSPE) workstation to produce seven fractions. The resulting fractions and the crude DCM:MeOH extract were tested in vitro against P. falciparum (NF54) ABS parasites using the malaria SYBR Green I based-fluorescence assay. Flash silica chromatography and mass-directed preparative high-performance liquid chromatography were utilised to isolate the active compounds. The isolated compounds were evaluated in vitro against P. falciparum asexual (NF54 and K1 strains) and sexual (gametocytes and gametes) stage parasites. Molecular docking was then used for the in silico prediction of targets for the isolated active compounds in P. falciparum.

RESULTS

The crude extract and two SPE fractions displayed good antiplasmodial activity with >97% and 100% inhibition of ABS parasites proliferation at 10 and 20 μg/mL, respectively. Following UPLC-MS analysis of these active fractions, a targeted purification resulted in the isolation of six compounds identified as aloesaponol I (1), aloesaponarin I (2), aloesaponol IV (3), β-sorigenin-1-O-methylether (4), emodin (5), and chrysophanol (6). Aloesaponarin I (2) was the most bioactive, compared to other isolated constituents, against P. falciparum ABS parasites exhibiting equipotency against the drug-sensitive (NF54) (IC₅₀ = 1.54 μg/mL (5 μM)) and multidrug-resistant (K1) (IC₅₀ = 1.58 μg/mL (5 μM)) strains. Aloesaponol IV (3) showed pronounced activity against late-stage (>90% stage IV/V) gametocytes (IC₅₀ = 6.53 μg/mL (22.6 μM)) demonstrating a 3-fold selective potency towards these sexual stages compared to asexual forms of the parasite (IC₅₀ = 19.77 ± 6.835 μg/mL (68 μM)). Transmission-blocking potential of aloesaponol IV (3) was validated by in vitro inhibition of exflagellation of male gametes (94% inhibition at 20 μg/mL). In silico studies identified β-hematin and DNA topoisomerase II as potential biological targets of compounds 2 and 3, respectively.

CONCLUSION

The findings from our study substantiate the traditional use of A. marlothii to treat malaria. To our knowledge, this study has provided the first report on the isolation and identification of antiplasmodial compounds from A. marlothii roots. Furthermore, our study has provided the first report on the transmission-blocking potential of one of the compounds from the genus Aloe, motivating for the investigation of other species within this genus for their potential P. falciparum transmission-blocking activity.

HPLC-Based Purification and Isolation of Potent Anti-HIV and Latency Reversing Daphnane Diterpenes from the Medicinal Plant Gnidia sericocephala (Thymelaeaceae)

Despite the success of combination antiretroviral therapy (cART), HIV persists in low- and middle-income countries (LMIC) due to emerging drug resistance and insufficient drug accessibility. Furthermore, cART does not target latently-infected CD4+ T cells, which represent a major barrier to HIV eradication. The “shock and kill” therapeutic approach aims to reactivate provirus expression in latently-infected cells in the presence of cART and target virus-expressing cells for elimination. An attractive therapeutic prototype in LMICs would therefore be capable of simultaneously inhibiting viral replication and inducing latency reversal. Here we report that Gnidia sericocephala, which is used by traditional health practitioners in South Africa for HIV/AIDS management to supplement cART, contains at least four daphnane-type compounds (yuanhuacine A (1), yuanhuacine as part of a mixture (2), yuanhuajine (3), and gniditrin (4)) that inhibit viral replication and/or reverse HIV latency. For example, 1 and 2 inhibit HIV replication in peripheral blood mononuclear cells (PBMC) by >80% at 0.08 µg/mL, while 1 further inhibits a subtype C virus in PBMC with a half-maximal effective concentration (EC50) of 0.03 µM without cytotoxicity. Both 1 and 2 also reverse HIV latency in vitro consistent with protein kinase C activation but at 16.7-fold lower concentrations than the control prostratin. Both 1 and 2 also reverse latency in primary CD4+ T cells from cART-suppressed donors with HIV similar to prostratin but at 6.7-fold lower concentrations. These results highlight G. sericocephala and components 1 and 2 as anti-HIV agents for improving cART efficacy and supporting HIV cure efforts in resource-limited regions.

Lobostemon trigonus (Thunb.) H. Buek, a medicinal plant from South Africa as a potential natural microbicide against HIV-1

ETHNOPHARMACOLOGICAL RELEVANCE

There have been different methods proposed to prevent the sexual transmission of HIV-1 and many of them have centered on the use of anti-retrovirals as microbicides. Given that a large section of the African population still relies on herbal medicine, Lobostemon trigonus (L. trigonus), a traditionally used medicinal plant in South Africa to treat HIV-1 was further investigated for its potential as a natural microbicide to prevent the sexual transmission of HIV-1.

METHODS

The aerial parts of L. trigonus were oven-dried at 80 °C, ground, extracted with boiling water for 30 min and then filtered. The aqueous extract produced was then bioassayed using different HIV-1 inhibition assays. The active components were purified and chemically profiled using ultra-performance liquid chromatography/quadrupole time-of flight mass spectrometry (UPLC-qTOF-MS). The mechanism of HIV-1 inhibition was determined by fusion arrest assay and time of addition assay. Molecular modelling and molecular dynamic simulations, using Schrödinger, were used to better understand the molecule's mechanism of entry inhibition by evaluating their docking affinity and stability against the gp120 of HIV-1.

RESULTS

The aqueous extract of this plant had a broad spectrum of activity against different subtypes of the virus; neutralizing subtype A, B and C in the TZM-bl cells, with IC₅₀ values ranging from 0.10 to 7.21 μg/mL. The extract was also inhibitory to the virus induced cytopathic effects in CEM-SS cells with an EC₅₀ of 8.9 μg/mL. In addition, it inhibited infection in peripheral blood mononuclear cells (PBMC) and macrophages with IC₅₀ values of 0.97 and 4.4 μg/mL, respectively. In the presence of vaginal and seminal simulants, and in human semen it retained its inhibitory activity albeit with a decrease in efficiency, by about 3-fold. Studies of the mode of action suggested that the extract blocked HIV-1 attachment to target cells. No toxicity was observed when the Lactobacilli strains, L. acidophilus, L. jensenii, and L. crispatus that populate the female genital tract were cultured in the presence of L. trigonus extract. UPLC-qTOF-MS analyses of the purified fraction of the extract, confirmed the presence of six compounds of which four were identified as rosmarinic acid, salvianolic acids B and C and lithospermic acid. The additional molecular dynamic simulations provided further insight into the entry inhibitory characteristics of salvianolic acid B against the HIV-1 gp120, with a stable pose being found within the CD4 binding site.

CONCLUSION

The data suggests that the inhibitory effect of L. trigonus may be due to the presence of organic acids which are known to possess anti-HIV-1 properties. The molecules salvianolic acids B and C have been identified for the first time in L. trigonus species. Our study also showed that the L. trigonus extract blocked HIV-1 attachment to target cells, and that it has a broad spectrum of activity against different subtypes of the virus; thus, justifying further investigation as a HIV-1 microbicide.

[Mesenteric cyst: case report and review of the literature]

Mesenteric and retroperitoneal cysts are rare intra-abdominal tumours with an incidence of 1/140.000 in surgery departments and 1/20.000 in paediatric departments. There are no pathognomonic signs or symptoms for the cysts. In the differential diagnosis lymphangiomas, sarcomas, adenocarcinomas and intestinal duplications should be considered. Diagnostic includes abdominal computed tomography, ultrasound and MRI. Barium enema examination or intravenous pyelogram may be used in special cases. Surgical treatment is indicated also in asymptomatic patients; laparoscopic approach is the "gold standard". Laparotomic approach should be used in the cases of impossibility of total enucleation or in the cases of malignant degeneration. Complete enucleation is the treatment of choice for retroperitoneal and mesenteric cysts. If this cannot be accomplished, the alternative should be the excision of the cyst or the marsupialization. In this paper we present a case of young man with a mesenteric cyst mimicking acute appendicitis.

Long-term survival after kidney and kidney-pancreas transplantation in diabetic patients

PURPOSE

To investigate the influence of diabetes mellitus on patient and graft survival among renal versus renal-pancreatic recipients.

METHODS

Among 270 renal transplants performed from 1985 to 2002, a total of 204 (75%) were in diabetic patients and 66 (25%) in nondiabetic patients. Among the 204 diabetic patients 161 (60%) kidneys were transplanted simultaneously with a pancreatic graft (SKPT group). The overall group of patient included 164 (61%) men and 106 (39%) women with mean time on dialysis of 31 +/- 21 months (range 0 to 126 months). The mean duration of diabetes was 24 +/- 7 years (range 5 to 51 years). Ninety-nine percent of the patients were on renal replacement therapy (79% hemodialysis and 20% peritoneal dialysis).

RESULTS

The overall rejection rate was similar (NS). Both patient and kidney graft survival rates were worse in diabetics. Patient survival was 82% at 5 years among patients undergoing SKPT, 60% in diabetics receiving only a kidney, and 88% in nondiabetic transplanted patients. Kidney graft survival at 5 years was 77% in diabetics receiving SKPT, 68% in diabetics receiving a kidney alone, and 82% in nondiabetic patients. Overall patient survival was significantly greater among nondiabetics (P =.002) or in diabetics who received SKPT compared with diabetics who only had a kidney transplant (P =.001).

CONCLUSIONS

This retrospective clinical evaluation confirms that combined pancreas and kidney transplantation should be the first choice to insulin-dependent diabetes mellitus (IDDM) patients with end-stage diabetic nephropathy.

Management of papillary microcarcinoma of the thyroid gland

DESIGN

To investigate the frequency, treatment and clinical behaviour of differentiated microcarcinoma of the thyroid gland (PTMC).

PATIENTS AND METHODS

Out of 376 patients submitted to surgical treatment for differentiated thyroid cancer from June 1980 to October 2003, 77 had been identified has having a PTMC (63 females, 14 males; mean age 43+/-13 years). Sixty-seven patients (87%) met the AMES risk definition for low (group I) and 10 (13%) for high-risk (group II) definition. The surgical procedures were lobo-isthmusectomy (n=14) or subtotal thyroidectomy (n=20) and total thyroidectomy (n=43) with node dissection in 15 cases. Follow-up ranging from 9 to 274 months (mean 124+/-84).

RESULTS

Overall patient survival rates were 100 and 94% at 20 years in groups I and II, respectively (p=ns). There were no significant differences in surgical complications and in survival in patients submitted to total thyroidectomy when compared to partial thyroid resection. The presence of cervical node metastasis did not affect patient survival (p=0.8). The overall mean survival time was 266 months.

CONCLUSIONS

Despite the overall excellent prognosis, PTMC was associated with a 1% disease-related mortality, a 2.5% local recurrence rate, 1% lymph-node recurrence rate, and 1% distant metastasis rate. We recommend total thyroidectomy accompanied by modified neck dissection if enlarged nodes are diagnosed.

Outcome of simultaneous kidney pancreas transplantation: a single center analysis

The aim of this study was to evaluate the outcome of simultaneous kidney pancreas transplantation (SKPT) by various surgical techniques. The 161 patients submitted to SKPT underwent the following: 36 pancreas with duct occlusion (from 1985 to 1989), 75 with whole pancreas with bladder diversion (from 1990 to 1998), and 50 whole pancreas with enteric diversion (40 with systemic and 10 with portal drainage) (from 1999 to September 2002). A positive effect on patient survival was evident using enteric diversion versus the duct occlusion group (P = .005), and versus the bladder diversion group (.035), and on pancreas graft survival in the enteric diversion versus the duct occlusion group (P < .028). These improvements may be due to refined donor and patient selection criteria, surgical technique, and immunosuppression.

Simultaneous pancreas-kidney transplantation: short- and long-term results

Simultaneous kidney and pancreas transplantation (SKPT) is the treatment of choice for a majority of type I diabetic patients with end-stage renal disease. With continual refinements in surgical technique and an evolving immunosuppressive arsenal, graft and patient survival have continually improved. The purpose of this study was to evaluate the short- and long-term results of SKPTs performed in 174 recipients from June 1985 to March 2003 including 37 segmental grafts with duct occlusion, 73 whole pancreas transplants with bladder diversion, and 64 whole pancreas grafts with enteric diversion. The series includes 160 cases with systemic drainage and 14 with portal drainage. In the segmental pancreas group, patient survival was 85%, 76%, and 53% with pancreas survival of 67%, 36%, and 15%, and kidney survival of 82%, 63%, and 15%, respectively, at 1, 5, and 10 years. Among the bladder diversion group, patient survival was 94%, 83%, and 73% pancreas survival 72%, 67%, and 65%, and kidney survival 89%, 78%, and 58%, respectively, 1, 5, and 10 years. Among the enter diversion group patient survival was 90% and 90% at 12 and 108 months, pancreas survival 80% and 65%, and kidney survival 85% and 85%, respectively. There were significant differences between curves of survival distribution according to the surgical technique applied for patients (P =.04), pancreas (P =.007), and kidney (P =.005). Based on the results from our study, the short- and long-term prognosis after SKPT is satisfactory, especially compared to the outcomes of long-term dialysis among patients with end-stage renal disease caused by type I diabetes.

Apolipoprotein E genotyping by capillary electrophoretic analysis of restriction fragments

We present the genotyping of apolipoprotein (apo) E by means of restriction fragment analysis of amplified genomic DNA by high-performance capillary electrophoresis and a replaceable non-gel-sieving matrix. This procedure streamlines the genotyping of apo E in large-scale population studies because of the automation and speed of capillary electrophoresis.

Anion-exchange HPLC analysis of biotinylated oligonucleotides

Biotinylated oligonucleotides combined with streptavidin-coated magnetic beads are commonly used in current molecular biology. Their quality and the level of incorporated biotin are essential for yielding good results in either solid-phase DNA sequencing or solid-phase purification procedures. This paper presents a very simple analytical test using anion-exchange HPLC and avidin to ascertain the quality of biotinylated oligonucleotides and to predetermine their ability to bind to avidin, which is a prerequisite for functionality in some solid-phase methods.

Fluorescence-based automated DNA sequencing by limited primer labeling

The applicability of automated DNA sequencing systems to sequencing strategies that require a large number of primers is limited by the necessity for expensive fluorescence-labeled oligonucleotides. Here we present a simple procedure that allows the use of unlabeled oligonucleotides to perform fluorescence-based DNA sequencing. This method is based on a limited primer extension that incorporates three deoxynucleotides, one of which carries a fluorescent moiety. The elongated fluorescent primer is then used in a standard T7 sequencing reaction. This labeling procedure is both economical and straightforward and offers a valid alternative to current fluorescence-labeling protocols. Results of this method with different DNA templates demonstrate the reliability of the protocol.

Mixed-mode fluorescent DNA sequencing

Fluorescence-based, automated DNA sequences represent one of the major advances in recent molecular biology. Two main technologies have been developed in this field: the single-label/four-lane system and the four-label/one-lane system. The following present the use of single-label-sequencing chemistry, which resembles traditional radioactive DNA sequencing, using the four-label system ABI 373A that expands its flexibility and obtains data that are immediately interpretable without software manipulation. This method has been named mixed-mode fluorescent DNA sequencing. Here we show one of its possible applications in molecular genetic analysis.

Introduction of magnetic beads in diagnosis: a simple and rapid method to detect mutations of beta globin gene, directly amplified from blood

In this communication we present the results obtained by the use of magnetic beads in diagnosis, for the identification of genetic variants at the molecular level by sequencing, in comparison with the more laborious method of the production of ssDNA with asymmetric PCR. We compared the two techniques studying variants of beta globin gene: Hb Abruzzo [beta 143 (H21) His -> Arg] and Hb D Los Angeles [beta 121 (GH4) Glu -> Gln].

Alteration of laminin production in small-cell lung carcinoma: possible correlation with the absence of the basement membrane

Basement membranes are frequently absent in small-cell lung cancer (SCLC). To study this phenomenon, the production of laminin by SCLC cells, both in vitro and in vivo, has been investigated and compared with the laminin production by lung carcinomas of other histotypes (non-SCLC, NSCLC). Immunoradiometric and immunoperoxidase tests, respectively, carried out on culture supernatants and cells using antilaminin rabbit antiserum, revealed that in 1 (H446) out of 8 SCLC cell lines tested and in the NSCLC line Calu3, laminin was detectable both in the culture medium and in the cytoplasm of the cells. After treatment of an SCLC-negative cell line (N592) with monensin, a molecule which inhibits protein secretion, laminin became detectable in the cytoplasm. Similar results were obtained by FACS analysis on cells permeabilized with saponin. Northern analysis indicated that the laminin B1 gene was transcribed. The level of mRNA for the B1 laminin subunit in the N592 cells was twice and 4 times higher than that found in the laminin-secreting Calu3 and H446 cell lines. The production of laminin in SCLC and NSCLC surgically resected samples using immunoperoxidase staining of cryostatic sections was also investigated. The results indicate that 85% of the NSCLC cases tested showed diffuse staining in the cytoplasm of the tumor cells and strong staining at the basement membrane level, whereas a similar staining was only found in 15% of the SCLC cases tested. The treatment of SCLC cells with differentiating agents in vitro has been shown to induce the adhesion of these cells. In fact, n-butyric acid induced the disaggregation of floating-clump cells and single-cell adhesion in the N592 line, whereas after treatment with retinoids the clumps of the N592 cells were still present, but 30% of these were found to adhere to the plate. However, no increase in the laminin production was found in the cytoplasmic or culture medium under these conditions.