[Features and evolution of patients with COVID-19 who required mechanical ventilation]. / Características y resultados de pacientes COVID-19 tratados con ventilación mecánica invasiva en Hospital San Juan de Dios. Marzo-junio 2020.

BACKGROUND: The overall mortality of patients with COVID-19 admitted to intensive care units is approximately 40%. AIM: To describe the characteristics of a cohort of patients with COVID-19 who required invasive mechanical ventilation due to severe hypoxemic acute respiratory failure at a general hospital in Santiago, Chile. MATERIAL AND METHODS: Review of medical records and follow up for 28 days of patients with COVID-19 confirmed by polymerase chain reaction who required invasive mechanical ventilation and who were admitted to the intensive care unit from March 24 to June 7, 2020. RESULTS: Data from 152 patients aged 58 (interquartile range (IQR) 47-65 years (66% men) was analyzed. As of July 5, 36 (24%) had died, 75 (49%) were discharged, 10 (7%) were still on invasive mechanical ventilation, 11 (7%) remained with tracheostomy but without invasive mechanical ventilation, and 20 (13%) were hospitalized in a basic unit. The median time on invasive mechanical ventilation among extubated patients was 14 days (IQR 10-21) and 121 (80%) were in the prone position. Patients who died were older, had a higher frequency of diabetes mellitus and a higher driving pressure at 7 days than those discharged alive from the intensive care unit. CONCLUSIONS: In this study mortality was lower than that reported in the first international studies, probably due to the selection of younger patients and greater knowledge of the disease.

[Diaphyseal osteoporotic nonunion of the humerus in elderly patients. Surgical treatment and long-term results]. / No-consolidación diafisaria de húmero en pacientes adultos con osteoporosis. Tratamiento quirúrgico y resultados a largo plazo.

INTRODUCTION: to evaluate the long term radiographic and functional results achieved in adult patients with osteoporotic, atrophic, non-unions of the diaphyseal humerus, treated surgically by open reduction and internal fixation with plates and bone graft. MATERIAL AND METHODS: we retrospectively evaluated 22 patients. Patient's age averaged 72 years. Time from initial trauma to definitive surgery averaged 18 months. Eleven patients were smokers, and four had active infection. Pre-operative Constant score and DASH score averaged 23.13 and 81.04, respectively. Pre-operative pain scale averaged 7.45 points. RESULTS: follow-up averaged 69 months. Union was achieved in all cases after an average of 4.68 months. DASH score at last follow-up averaged 20.27 points and Constant score 79.31 points. Analog pain scale averaged 0.77 points. Stabilization was performed using locking blade plates in 12 non-unions, locking compression plates in six cases, and double plating in four non-unions. Patients with active infection were treated in two stages using Masquelet's technique. Bone graft was associated in all cases (cancellous iliac crest autograft in 17, allograft in three, and combined structural allograft and cancellous autograft in two). Two grams of vancomycin powder were associated to the bone graft in all cases. CONCLUSION: the use of open reduction and internal fixation with plates associated to bone graft with local antibiotics, aloud achieving bony union and good predictable long-term objective and subjective functional results in all cases, without major complications or the need of further surgical intervention.

INTRODUCCIÓN: evaluar los resultados radiográficos y funcionales obtenidos a largo plazo en pacientes adultos que presentaron no-consolidaciones atróficas diafisarias de húmero asociadas a osteoporosis; tratadas quirúrgicamente mediante reducción abierta y fijación interna con placas e injerto óseo. MATERIAL Y MÉTODOS: evaluamos retrospectivamente 22 pacientes, con edad promedio de 72 años, el tiempo desde el trauma inicial hasta la cirugía definitiva promedió, 18 meses. Once pacientes eran fumadores y cuatro presentaban infección activa. El score de Constant y el DASH preoperatorios promediaron 23.13 y 81.04, respectivamente. El valor de la escala analógica del dolor preoperatorio promedió 7.45 puntos. RESULTADOS: el seguimiento promedió 69 meses. Se obtuvo la consolidación en todos los casos, luego de un promedio de 4.68 meses. Al último seguimiento, los valores del DASH promediaron 20.27 puntos y el score de Constant promedió 79.31 puntos. La escala analógica del dolor promedió 0.77 puntos. La estabilización se realizó utilizando clavos placa bloqueados en 12 no-consolidaciones, placas bloqueadas de compresión en seis y doble placa en cuatro. Los pacientes con infección activa fueron tratados en dos etapas utilizando la técnica descripta por Masquelet. Se asoció injerto óseo en todas las reconstrucciones (autoinjerto esponjoso de cresta ilíaca en 17, aloinjerto en tres y se combinó aloinjerto estructural con autoinjerto esponjoso en dos). Dos gramos de vancomicina en polvo fueron asociados localmente al injerto óseo. CONCLUSIÓN: la combinación de reducción abierta y fijación interna con placas e injerto óseo permitió obtener la consolidación y resultados funcionales objetivos y subjetivos buenos y predecibles a largo plazo en todos los casos, sin complicaciones mayores ni la necesidad de intervenciones quirúrgicas sucesivas.

No-consolidación diafisaria de húmero en pacientes adultos con osteoporosis. Tratamiento quirúrgico y resultados a largo plazo / Diaphyseal osteoporotic nonunion of the humerus in elderly patients. Surgical treatment and long-term results

Resumen: Introducción: evaluar los resultados radiográficos y funcionales obtenidos a largo plazo en pacientes adultos que presentaron no-consolidaciones atróficas diafisarias de húmero asociadas a osteoporosis; tratadas quirúrgicamente mediante reducción abierta y fijación interna con placas e injerto óseo. Material y métodos: evaluamos retrospectivamente 22 pacientes, con edad promedio de 72 años, el tiempo desde el trauma inicial hasta la cirugía definitiva promedió, 18 meses. Once pacientes eran fumadores y cuatro presentaban infección activa. El score de Constant y el DASH preoperatorios promediaron 23.13 y 81.04, respectivamente. El valor de la escala analógica del dolor preoperatorio promedió 7.45 puntos. Resultados: el seguimiento promedió 69 meses. Se obtuvo la consolidación en todos los casos, luego de un promedio de 4.68 meses. Al último seguimiento, los valores del DASH promediaron 20.27 puntos y el score de Constant promedió 79.31 puntos. La escala analógica del dolor promedió 0.77 puntos. La estabilización se realizó utilizando clavos placa bloqueados en 12 no-consolidaciones, placas bloqueadas de compresión en seis y doble placa en cuatro. Los pacientes con infección activa fueron tratados en dos etapas utilizando la técnica descripta por Masquelet. Se asoció injerto óseo en todas las reconstrucciones (autoinjerto esponjoso de cresta ilíaca en 17, aloinjerto en tres y se combinó aloinjerto estructural con autoinjerto esponjoso en dos). Dos gramos de vancomicina en polvo fueron asociados localmente al injerto óseo. Conclusión: la combinación de reducción abierta y fijación interna con placas e injerto óseo permitió obtener la consolidación y resultados funcionales objetivos y subjetivos buenos y predecibles a largo plazo en todos los casos, sin complicaciones mayores ni la necesidad de intervenciones quirúrgicas sucesivas.

Abstract: Introduction: to evaluate the long term radiographic and functional results achieved in adult patients with osteoporotic, atrophic, non-unions of the diaphyseal humerus, treated surgically by open reduction and internal fixation with plates and bone graft. Material and methods: we retrospectively evaluated 22 patients. Patient's age averaged 72 years. Time from initial trauma to definitive surgery averaged 18 months. Eleven patients were smokers, and four had active infection. Pre-operative Constant score and DASH score averaged 23.13 and 81.04, respectively. Pre-operative pain scale averaged 7.45 points. Results: follow-up averaged 69 months. Union was achieved in all cases after an average of 4.68 months. DASH score at last follow-up averaged 20.27 points and Constant score 79.31 points. Analog pain scale averaged 0.77 points. Stabilization was performed using locking blade plates in 12 non-unions, locking compression plates in six cases, and double plating in four non-unions. Patients with active infection were treated in two stages using Masquelet's technique. Bone graft was associated in all cases (cancellous iliac crest autograft in 17, allograft in three, and combined structural allograft and cancellous autograft in two). Two grams of vancomycin powder were associated to the bone graft in all cases. Conclusion: the use of open reduction and internal fixation with plates associated to bone graft with local antibiotics, aloud achieving bony union and good predictable long-term objective and subjective functional results in all cases, without major complications or the need of further surgical intervention.

Características y resultados de pacientes COVID-19 tratados con ventilación mecánica invasiva en Hospital San Juan de Dios. Marzo-junio 2020

Background: The overall mortality of patients with COVID-19 admitted to intensive care units is approximately 40%. Aim: To describe the characteristics of a cohort of patients with COVID-19 who required invasive mechanical ventilation due to severe hypoxemic acute respiratory failure at a general hospital in Santiago, Chile. Material and Methods: Review of medical records and follow up for 28 days of patients with COVID-19 confirmed by polymerase chain reaction who required invasive mechanical ventilation and who were admitted to the intensive care unit from March 24 to June 7, 2020. Results: Data from 152 patients aged 58 (interquartile range (IQR) 47-65 years (66% men) was analyzed. As of July 5, 36 (24%) had died, 75 (49%) were discharged, 10 (7%) were still on invasive mechanical ventilation, 11 (7%) remained with tracheostomy but without invasive mechanical ventilation, and 20 (13%) were hospitalized in a basic unit. The median time on invasive mechanical ventilation among extubated patients was 14 days (IQR 10-21) and 121 (80%) were in the prone position. Patients who died were older, had a higher frequency of diabetes mellitus and a higher driving pressure at 7 days than those discharged alive from the intensive care unit. Conclusions: In this study mortality was lower than that reported in the first international studies, probably due to the selection of younger patients and greater knowledge of the disease.

Extensor carpi ulnaris problems at the wrist--classification, surgical treatment and results.

Twenty-eight extensor carpi ulnaris lesions at the wrist were treated surgically between 1990 and 2002. Fifteen patients had an isolated extensor carpi ulnaris tenosynovitis or tendinopathy, five had extensor carpi ulnaris dislocation, four had an extensor carpi ulnaris subluxation and four had an extensor carpi ulnaris rupture. Seventeen patients first developed their symptoms while playing sports. At a mean follow-up of 23 months, twenty-two patients had returned to their previous activities. Seven of the 27 patients had lost more than 30% of their grip strength and five had restricted wrist motion. Two needed an extensor carpi ulnaris tenolysis. Pure isolated extensor carpi ulnaris lesions are rare and associated ulnar sided lesions (eleven triangular fibrocartilage complex tears and four lunotriquetral ligament tears), as well as possible predisposing factors (seven anomalous tendon slips, four ulnar styloid non-unions and one flat extensor carpi ulnaris tendon groove), were frequent. A classification of extensor carpi ulnaris tendon and subsheath lesions was developed to allow the surgeon to adequately evaluate the different components of these lesions.

Minimally invasive plate osteosynthesis in distal radius fractures with metaphyseal extension: A series of 13 cases.

UNLABELLED: To evaluate objective and subjective outcomes after minimally invasive volar locked plate fixation of distal radius fractures with metaphyseal extension, we retrospectively evaluated 13 patients with unstable distal radius fractures with metaphyseal extension, treated by minimally invasive volar locked plating. Patients' average age was 41 years. Two volar incisions, 2 to 3cm long, were made; indirect reduction was performed and a volar locked T-plate was placed submuscularly under fluoroscopy guidance. Twelve fractures healed after an average of 2.46 months; one patient needed revision due to a new injury. The plate had to be removed in one patient. On X-rays, radial height averaged 12.78mm, radial inclination averaged 21.34° and volar tilt averaged 8.22°. Flexion averaged 75°, extension 71.5°, pronation 82.08° and supination 83.08°. Grip strength averaged 83.75% of the contralateral wrist. The DASH score averaged 13.91 points and pain assessed on VAS averaged 0.92 points. In unstable distal radius fractures with metaphyseal extension, minimally invasive plate osteosynthesis using volar locked plates led to good reduction and stable fixation, with low pain levels, and good functional and esthetic results. Indirect reduction techniques, fluoroscopy, and restoration of radial length, rotation and alignment, are necessary to achieve these outcomes. LEVEL OF EVIDENCE: IV.

Promiscuous subunit interactions: A possible mechanism for the regulation of protein kinase CK2.

Protein kinase CK2 is a ubiquitous eukaryotic ser/thr protein kinase. The active holoenzyme is a heterotetrameric protein composed of catalytic (α and α') and regulatory (ß) subunits that phosphorylates many different protein substrates and appears to be involved in the regulation of cell division. Despite important structural studies, the intimate details of the interactions of the α catalytic subunits with the ß regulatory subunits are unknown. Recent evidence that indicates that both CK2 subunits can interact promiscuously with other proteins in a manner that excludes the binding of their complementary CK2 partners has opened the possibility that the phosphorylating activity of this enzyme may be regulated in a novel way. These alternative interactions could limit the in vivo availability of CK2 subunits to generate fully active holoenzyme CK2 tetramers. Likewise, variations in the ratio of α- and ß-subunits could determine the activity of several phosphorylating and dephosphorylating activities. The promiscuity of the CK2 subunits can be extrapolated to a more widespread phenomenon in which "wild-card" proteins could act as general switches by interacting and regulating several catalytic activities. J. Cell. Biochem. Suppls. 30/31:129-136, 1998. © 1998 Wiley-Liss, Inc.

Folylpolyglutamate analogs can inhibit casein kinase II from Xenopus laevis.

Polyglutamate analogs of folate and related compounds were tested as inhibitors of casein kinase II (CK II) obtained from Xenopus laevis. The inhibitory capacity of the pteroyl, 4-amino-10-methyl pteroyl (the methotrexate aromatic moiety), and p-aminobenzoil derivatives increased as the number of gamma-glutamates attached went from 2 to 7. The nature of the aromatic head, group was also important since hexa-gamma-glutamatic acid had no inhibitory activity while the folylhexaglutamate derivatives were strong inhibitors with relative potency of methotrexate greater than pteroyl greater than p-aminobenzoic acid. The inhibition of CK II by methotrexate gamma-pentaglutamate was competitive with casein and showed an apparent K(i) of 90 microM.

Nucleic acids can regulate the activity of casein kinase II.

Casein kinase II purified from nuclei of Xenopus laevis oocytes is inhibited by several specific nucleic acids. This kinase, the main phosphorylating activity of the oocyte nucleus, is markedly inhibited by poly U at 10 micrograms/ml, and this polymer is a competitive inhibitor of the phosphorylation of the substrate casein (Kiapp 80 nM). M 13 phage ssDNA and unfractionated yeast tRNA also inhibit between 50 and 200 micrograms/ml. Poly C, poly A, poly AG, dsDNA and Escherichia coli rRNA do not alter activity significantly at similar concentrations. Inhibitions are reversed by RNase (poly U, tRNA) or S1 nuclease (ssDNA). Oocyte casein kinase I or rabbit cAMP-dependent protein kinase are not inhibited by poly U at 200 micrograms/ml. The sensitivity of the casein kinase II to these inhibitors suggests a regulatory role for nucleic acids in nuclear phosphorylation reactions.

Oncogenic ras protein induces meiotic maturation of amphibian oocytes in the presence of protein synthesis inhibitors.

Microinjection of the activated ras oncogenic protein can induce the meiotic maturation of Xenopus laevis oocytes, a process that can also be triggered by progesterone or high concentrations of insulin. Cycloheximide and puromycin, well-known inhibitors of protein synthesis, block the maturation process induced by progesterone and insulin but do not affect the maturation caused by H-raslys12 protein microinjection. Theophylline, an inhibitor of cAMP phosphodiesterase that also affects oocyte protein synthesis, does cause a partial inhibition of ras protein-induced maturation. These findings indicate that ras protein acts on the oocyte maturation process at a point that is downstream of the protein synthesis requirement, a characteristic shared with the maturation promoting factor, an activity that appears in oocytes and mitotic cells at the onset of cell division.

The cDNAs coding for the alpha- and beta-subunits of Xenopus laevis casein kinase II.

Using a lambda gt10 cDNA library obtained from Xenopus laevis oocytes and probes derived from the known sequences of the human and Drosophila genes, a cDNA coding for the alpha-subunit of the X. laevis casein kinase II was isolated. The coding sequence of this clone determines a polypeptide of 350 amino acids. The X. laevis sequence is 98% identical to the human and rat proteins in the first 323 amino acids. Using the polymerase chain reaction to generate a 370-nucleotide-long probe, it was possible to clone and sequence a cDNA of 900 nucleotides that coded for the X. laevis beta-subunit of casein kinase II. The derived protein sequence is 215 amino acids long and again shows an extraordinary degree of conservation with other species.

Site-directed mutants of the beta subunit of protein kinase CK2 demonstrate the important role of Pro-58.

The following amino acids of the Xenopus laevis beta subunit of protein kinase CK2 (casein kinase 2) were changed to alanine: Pro-58 (beta P-->A); Asp-59 and Glu-60 and Glu-61 (beta DEE-->AAA); His-151-153 (beta HHH-->AAA). The last 37 amino acids of the carboxyl end were deleted (beta delta 179-215). Stimulation of CK2 alpha catalytic subunit activity was measured with casein as substrate and the following relative activities were observed: beta P-->A > beta DEE-->AAA >>> beta WT > beta HHH-->AAA >>> beta delta 179-215. The beta DEE-->AAA and beta P-->A were similar to beta WT in reducing CD2 alpha binding to DNA but beta delta 179-215 was less active. The results indicate that both Pro-58 and the surrounding acidic cluster play roles in dampening the activation of CK2 alpha and that the carboxyl end of beta is involved in the interaction with CK2 alpha.

The phosphorylation of nucleoplasmin by casein kinase-2 is resistant to heparin inhibition.

Highly purified preparations of casein kinase-2 from the nuclei of Xenopus laevis oocytes and from calf thymus can phosphorylate in vitro purified nucleoplasmin from X. laevis oocytes and eggs. The phosphorylation of nucleoplasmin by both kinase preparations is quite insensitive to heparin in contrast with casein phosphorylation which is completely abolished by heparin concentrations above 10 micrograms/ml. However, the phosphorylation of nucleoplasmin and casein are inhibited in a very similar fashion by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), a well characterized specific inhibitor of casein kinase-2. Similarly, nucleoplasmin phosphorylation by the oocyte enzyme can be stimulated several-fold by spermine, another characteristic of this enzyme. These findings indicate that the phosphorylation of nucleoplasmin by purified casein kinase-2, while showing typical response to DRB and spermine, exhibits anomalous behavior in its resistance to heparin inhibition. It is possible that the large clusters of acidic amino acids in nucleoplasmin permit this substrate to interact with the enzyme more efficiently than other protein substrates. Heparin is generally considered a potent and specific inhibitor of casein kinase-2. This study, however, questions the validity of utilizing heparin inhibition as a criterion for casein kinase-2 involvement.

An inactive mutant of the alpha subunit of protein kinase CK2 that traps the regulatory CK2beta subunit.

Protein kinase CK2 (casein kinase 2) is a ubiquitous Ser/Thr protein kinase involved in cell proliferation. Mutation of the alpha subunit of the Xenopus laevis CK2 to change aspartic acid 156 to alanine (CK2alphaA156) resulted in an inactive enzyme. The CK2alphaA156 mutant, however, binds the regulatory subunit as measured by retention of beta on a nickel chelating column mediated by (His)6-tagged CK2alphaA156. Addition of CK2alphaA156 also caused beta to shift sedimentation in a sucrose gradient from a beta2 dimer (52 kDa) to an alpha2beta2 tetramer (130,000 kDa). CK2alphaA156 can trap the beta subunit in an inactive complex reducing the stimulation of casein phosphorylation caused by addition of beta to wild-type alpha. This competitive effect depends on the ratio of alpha/alphaA156 and on the amount of beta available. Since beta inhibits the phosphorylation of calmodulin by CK2alpha, the addition of CK2alphaA156, in this case, increases calmodulin phosphorylation by the alpha and beta combination. These results suggest that CK2alphaA156 may be a useful dominant-negative mutant that can serve to explore the multiple functions of CK2beta.

Activity of the E75E76 mutant of the alpha subunit of casein kinase II from Xenopus laevis.

The cDNA gene coding for the alpha subunit of Xenopus laevis casein kinase II was mutated using the overlap extension PCR method. The mutation substituted glutamic acids for Lys75 and Lys76, changing the charge distribution of a very basic sequence found in the alpha subunit. Expression of the mutated cDNA in a pT7-7 vector in E. coli yielded an active mutant recombinant protein that was extensively purified. This mutant was not significantly affected in its app. Km for casein or a model peptide substrate, nor in its interaction with the activating beta subunit. Inhibition by quercetin and by 5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole was also the same for mutant and wild type subunits. However, the CKII alpha E75E76 mutant was at least one order of magnitude less sensitive to inhibition by polyanionic inhibitors such as heparin, poly U, copolyglutamic acid:tyrosine (4:1) and 2,3 diphosphoglycerate.

Copolymers of glutamic acid and tyrosine are potent inhibitors of oocyte casein kinase II.

Polypeptides rich in glutamic acid are strong inhibitors purified from isolated nuclei of Xenopus laevis oocytes of casein kinase II. The presence of tyrosine in these peptides greatly enhances their inhibitory capacity. Using casein as a substrate, copolyglu:tyr (4:1) has an I50 value of 20 nM, 250 fold lower than that of polyglutamic acid which is 5 microM. A similar large difference is observed when a synthetic peptide is used as substrate. The inhibition of copolyglu:tyr is competitive with casein and can be completely reversed by high ionic strength. The relative inhibitory capacity of the polypeptides tested, in descending order, is copolyglu:tyr (4:1) greater than copolyglu:tyr (1:1) greater than polyglu greater than copolyglu:phe (4:1) greater than copolyglu:ala (6:4) greater than copolyglu:leu (4:1). The high affinity for tyrosine-containing acid peptides is shared by rat liver and yeast casein kinase II so that it seems to be a general property of these enzymes.

Cloning and chromosomal localization of the gene coding for human protein kinase CK1.

A cDNA clone coding for human protein kinase CK1 (casein kinase 1) has been isolated and sequenced demonstrating that it corresponds to a homolog of the CK1 alpha form found in bovine brain. The derived amino acid sequence of the human CK1 alpha is identical to the bovine counterpart except that it contains 12 extra amino acids at the carboxyl end. Using this cDNA sequence and PCR amplification, YAC genomic clones that contain this human CK1 alpha sequence have been isolated. These YACs have been used for fluorescent in situ hybridization in order to localize the human CK1 alpha gene to chromosome 13q13.

Effect of metal ions on the activity of casein kinase II from Xenopus laevis.

Casein kinase II purified from the nuclei of Xenopus laevis oocytes as well as the recombinant alpha and beta subunits of the X. laevis CKII, produced in E. coli from the cloned cDNA genes, were tested with different divalent metal ions. The enzyme from both sources was active with either Mg2+, Mn2+, or Co2+. Optimal concentrations were 7-10 mM for Mg2+, 0.5-0.7 mM for Mn2+ and 1-2 mM for Co2+. In the presence of Mn2+ or Co2+ the enzyme used GTP more efficiently than ATP as a phosphate donor while the reverse was true in the presence of Mg2+. The apparent Km values for both nucleotide triphosphates were greatly decreased in the presence of Mn2+ as compared with Mg2+. Addition of Zn2+ (above 150 microM) to an assay containing the optimal Mg2+ ion concentration caused strong inhibition of both holoenzyme and alpha subunit. Inhibition of the holoenzyme by 400 microM Ni2+ could be reversed by high concentrations of Mg2+ but no reversal of this inhibition was observed with the alpha subunit.

Involvement of asparagine 118 in the nucleotide specificity of the catalytic subunit of protein kinase CK2.

Protein kinase CK2 is a heteromeric enzyme with catalytic (alpha) and regulatory (beta) subunits which form an alpha2beta2 holoenzyme and utilizes both ATP and GTP as nucleotide substrate. Site-directed mutagenesis of CK2alpha subunit was used to study this capacity to use GTP. Deletion of asparagine 118 (alpha(deltaN118)) or the mutant alphaN118E gives a 5-6-fold increase in apparent Km for GTP with little effect on the affinity for ATP. Mutants alphaN118A and alphaD120N did not alter significantly the Km for either nucleotide. CK2alphaN118 has an apparent Ki for inosine 5' triphosphate 5-fold higher than wild-type and is very heat labile. These studies complement recent crystallographic data indicating a role for CK2alpha asparagine 118 in binding the guanine base.

Oocyte adenylyl cyclase contains Ni, yet the guanine nucleotide-dependent inhibition by progesterone is not sensitive to pertussis toxin.

Membranes were obtained from Xenopus laevis oocytes after removal of follicular cells by collagenase treatment. [32P]ADP-ribosylation with pertussis toxin showed them to contain a single Mr = 40000 substrate for this toxin that co-migrates on sodium dodecylsufate-polyacrylamide gel electrophoresis with pure human erythrocyte Ni, the inhibitory regulatory component of adenylyl cyclase. [32P]ADP-ribosylation of oocyte membranes with cholera toxin also showed presence of a single substrate but of Mr = 42000. These results indicate, that the adenylyl cyclase system of oocytes, like that of somatic cells and unlike that of spermatozoids, contains the catalytic unit C and both of the known regulatory N components. The possible susceptibility to pertussis toxin of the guanine nucleotide-dependent inhibition of oocyte adenylyl cyclase by progesterone was investigated. This action of progesterone is mediated by a membrane bound receptor as opposed to a receptor of cytosolic or nuclear localization. However, the inhibitory effect of progesterone was unaffected by pertussis toxin, even though the oocyte membrane Ni was fully ADP-ribosylated with pertussis toxin, as revealed by lack of further [32P]ADP-ribosylation on subsequent re-incubation with pertussis toxin. These results indicate that the action of progesterone, in spite of being nucleotide-dependent, is either not mediated by Ni, suggesting the existence of an additional nucleotide regulatory component, or if mediated by Ni, involves a mode of regulation of this coupling protein that is different from that by which all other inhibitory hormones act on adenylyl cyclase.